benilla-octo/crates/benilla-app/assets/ui/TrainerFrame.xml

<Ui>
    <!--
        benilla's class/profession trainer window (decisions 0237/0247/0251), a faithful port of the
        TBC-backported `Blizzard_TrainerUI` addon the director's client runs (0246): a client-sorted,
        collapsible **skill-line tree** with a **dropdown** state filter and a real **scroll bar**. The
        window art/geometry are the real 1.12 `ClassTrainerFrame` (MerchantFrame.xml's four-quadrant-slab
        idiom); the list/sort/collapse/filter logic is transcribed from `Blizzard_TrainerUI.lua` onto
        benilla's engine (`crates/benilla-ui/src/script/trainer.rs`, which builds the tree — decision
        0247) + the shared faux-scroll kit (ScrollTemplates.xml, decision 0251). This REPLACES the
        earlier flat-list placeholder (git has it): flat state-as-category rows + inline sort checkboxes
        + a chunk-local scroll offset, which stood in until the tree/scrollbar/dropdown landed.

        Modeled on the two known-good dressed windows for the framing:
          - MerchantFrame.xml — the 384×512 four-quadrant window art (no <Backdrop>: the art IS the
            frame), the NPC-session lifecycle (RegisterEvent trio + PLAYER_MONEY, SHOW/UPDATE/CLOSED
            dispatch, OnShow/OnHide PlaySound with CloseTrainer() on hide), the "npc" model-portrait
            binding, and the reference's own two money frames (detail cost + player purse). The close X reuses
            the minimize-button art (this engine ships no UIPanelCloseButton).
          - QuestLogFrame.xml — the list-row Button template shape ($parent-named child regions wired in
            <OnLoad>) and the persistent selection-highlight Frame (a child Frame whose ARTWORK Texture
            renders when Show()n, moved onto the selected visible row).

        WHAT'S NEW vs. the placeholder (decision 0247's tree, 0251's scroll bar):
          - THE LIST IS A TREE. GetTrainerServiceInfo(i) now returns interleaved "header" rows (a skill
            line's name, +/- fold) and service rows (name/state), 1-based into the VISIBLE tree. Update
            renders each row by type; a header click folds its group, a service click selects it.
          - THE FILTER IS A DROPDOWN. BenillaTrainerFilterDropDown (over UIDropDownMenu.xml's kit) with
            three keepShownOnClick check rows (Available/Unavailable/Already Known) driving the engine's
            state-visibility filter — replacing the three inline sort checkboxes. Its three states are
            SAVED VARIABLES (decision 1128): defaults 1/1/0 at file scope — "Already Known" starts OFF,
            the shipped 1.12.1 Blizzard_TrainerUI.lua:6-9's own values — restored from
            benilla/saved-variables.lua at load, and pushed into the engine on show because the list
            builder resets its mask on every packet.
          - THE SCROLL BAR IS REAL. BenillaTrainerListScrollFrame (FauxScrollFrameTemplate): a
            draggable Slider bar + up/down step arrows over the fixed 11 rows (the faux-scroll re-binds
            rows to a moving offset — it never really scrolls a child). The wheel still lives on the
            WINDOW (the engine bubbles a spin up the parent chain, so a spin over a row reaches here).
          - COLLAPSE WORKS. The "All" tab collapses/expands every group (Collapse/ExpandTrainerSkillLine(0));
            its +/- icon reflects whether all groups are folded (the backport's numHeaders/notExpanded).

        FLAT layout — a CHOICE, and it was written down here as a constraint that does not exist.
        This block used to claim "a child <Frame> shown at runtime does not render its own <Layers>
        FontStrings in this engine". That is FALSE, and it was propagated from here into two more
        windows before anyone probed it (decision 1517): MailFrame's own SendMailTitleText lives in a
        runtime-shown pane's Layers and has rendered correctly the whole time. The detail-pane
        FontStrings + the title/greeting do live on BenillaTrainerFrame's OWN <Layers>, and that is
        fine — it is simply one way to lay this out, not the only one available. Per-row regions live
        on the row Button template. The detail is a FIXED (non-scrolling) pane
        (our descriptions are empty for now) — no real ScrollFrame, unlike the ref's DetailScrollFrame.

        Adaptations / deviations (flagged):
          - TITLE: the trainer's NAME rides arg1 of TRAINER_SHOW/UPDATE (the app resolves the creature
            name ask-once via the NameCache — the MerchantFrame vendor-name precedent); "Trainer" until
            it lands.
          - PORTRAIT: the "npc" unit-token model bake (MerchantFrame's binding — the interaction NPC's face).
          - GlobalStrings the ref reads (REQUIRES_LABEL, TRAINER_REQ_*, COSTS_LABEL, the labels) are
            defined LOCALLY below as the byte-exact 1.12 enUS values (interface.MPQ GlobalStrings.lua,
            line-cited); NORMAL/GRAY/HIGHLIGHT_FONT_COLOR are Fonts.xml globals.
          - The affordability RED-TINT of the cost is the reference's own SetMoneyFrameColor (1937).
          - The profession-confirm StaticPopup is skipped for v1 (Train buys directly); a later refinement.

        Registers at the left UIPanel slot like Gossip/Merchant/Quest/QuestLog (UiPanels.xml) — opening
        it competes for/replaces those. It IS an NPC session: CloseTrainer() fires on hide, and the
        standardized range guard (crate::ui_session) client-side-closes it when the player walks away.
    -->
    <Script><![CDATA[
        -- ── GlobalStrings / labels the ref reads (byte-exact 1.12 enUS, interface.MPQ) ────────────────
        -- Chunk-local upvalues: the global functions below close over them; inline XML handlers (separate
        -- chunks) can't, so every handler routes to a function here. `_RED` variants redden only the
        -- number/name (met = white, unmet = red), exactly as the real requirements line reads.
        local PARENS_TEMPLATE = "(%s)"                      -- GlobalStrings.lua:2468
        local REQUIRES_LABEL  = "Requires:"                 -- REQUIRES_LABEL (2768)
        local UNKNOWN_LABEL   = "Unknown"                   -- UNKNOWN (3860)
        local FILTER_LABEL    = "Filter"                    -- FILTER (1297)
        local TRAINER_REQ_LEVEL          = "Level |cffffffff%d|r"        -- TRAINER_REQ_LEVEL (3739)
        local TRAINER_REQ_LEVEL_RED      = "Level |cffff2020%d|r"        -- TRAINER_REQ_LEVEL_RED (3740)
        local TRAINER_REQ_SKILL_RANK     = "%s (|cffffffff%d|r)"         -- TRAINER_REQ_SKILL_RANK (3741)
        local TRAINER_REQ_SKILL_RANK_RED = "%s (|cffff2020%d|r)"         -- TRAINER_REQ_SKILL_RANK_RED (3742)
        local TRAINER_REQ_ABILITY        = "|cffffffff%s|r"             -- TRAINER_REQ_ABILITY (3737)
        local TRAINER_REQ_ABILITY_RED    = "|cffff2020%s|r"             -- TRAINER_REQ_ABILITY_RED (3738)
        -- ── The state filter's three SAVED VARIABLES (decision 1128) ─────────────────────────────────
        -- The reference's own globals, values and mechanism: Blizzard_TrainerUI.lua:6-9 assigns these
        -- at FILE SCOPE and its `.toc` declares them `## SavedVariables`; the client executes the
        -- saved file over them AFTER this file loads and BEFORE the load event, so a remembered value
        -- wins over the default. benilla's ported UI is one FrameXML tree rather than addons, so the
        -- declaration rides `RegisterForSave` (FrameXML's own API for its 38 globals) and the same
        -- ordering is the app's load seam. File scope is load-bearing: assign these in OnLoad and the
        -- default would clobber the restored value every launch.
        TRAINER_FILTER_AVAILABLE   = 1
        TRAINER_FILTER_UNAVAILABLE = 1
        TRAINER_FILTER_USED        = 0
        RegisterForSave("TRAINER_FILTER_AVAILABLE")
        RegisterForSave("TRAINER_FILTER_UNAVAILABLE")
        RegisterForSave("TRAINER_FILTER_USED")

        local LABEL_AVAILABLE   = "Available"               -- AVAILABLE (84)
        local LABEL_UNAVAILABLE = "Unavailable"             -- UNAVAILABLE (3840)
        local LABEL_USED        = "Already Known"           -- USED (3868)
        -- The font colour codes the dropdown rows wrap their labels in (GlobalStrings.lua: the *_CODE
        -- family) — green/red/gray, closed with |r.
        local GREEN_CODE = "|cff20ff20"
        local RED_CODE   = "|cffff2020"
        local GRAY_CODE  = "|cff808080"
        local CODE_CLOSE = "|r"

        -- CLASS_TRAINER_SKILLS_DISPLAYED / CLASS_TRAINER_SKILL_HEIGHT (ref Blizzard_TrainerUI.lua:2-3).
        local BENILLA_TRAINER_ROWS = 11
        local BENILLA_TRAINER_ROW_HEIGHT = 16

        -- ── Detail pane ─────────────────────────────────────────────────────────────────────────────
        -- Nothing selected → blank every detail region: a FontString "hides" via SetText(""), while the
        -- icon Button + coin frames Hide. Predates region Show/Hide (region.rs has the real pair now);
        -- equivalent either way, so the blank-text idiom stays.
        function BenillaTrainer_HideDetails()
            getglobal("BenillaTrainerSkillName"):SetText("")
            getglobal("BenillaTrainerSkillRequirements"):SetText("")
            getglobal("BenillaTrainerSkillDescription"):SetText("")
            getglobal("BenillaTrainerCostLabel"):Hide()
            getglobal("BenillaTrainerSkillIcon"):Hide()
            getglobal("ClassTrainerDetailMoneyFrame"):Hide()
            getglobal("BenillaTrainerTrainButton"):Disable()
        end

        -- Fill the detail pane for the selected service `id` (1-based visible index) — the transcribed
        -- ClassTrainer_SetSelection detail half: name/sub name, the Requires: string (built term-for-term
        -- as the ref does), the icon, the cost coins + label, the description, and Train's enable state.
        function BenillaTrainer_ShowDetails(id)
            local name = GetTrainerServiceInfo(id)
            getglobal("BenillaTrainerSkillName"):SetText(name or UNKNOWN_LABEL)
            -- The detail header shows the spell NAME only — no "(Rank N)" beside it. A deliberate
            -- divergence from the ref (which sets a ClassTrainerSubSkillName subtext here): the rank is
            -- already on the spell's list row, so a second copy floated to the right of the name just
            -- read as clutter (director's call).

            local icon = getglobal("BenillaTrainerSkillIcon")
            icon:SetNormalTexture(GetTrainerServiceIcon(id) or BENILLA_FALLBACK_ICON)
            icon:Show()

            -- Requirements string (ref term-for-term): level gate, skill gate, each prerequisite ability;
            -- each red when unmet (hasReq nil). Our feed has no pet-learn / step requirements.
            local requirements = ""
            local separator = ""
            local reqLevel = GetTrainerServiceLevelReq(id)
            if reqLevel and reqLevel > 1 then
                separator = ", "
                if (UnitLevel("player") or 0) >= reqLevel then
                    requirements = requirements .. format(TRAINER_REQ_LEVEL, reqLevel)
                else
                    requirements = requirements .. format(TRAINER_REQ_LEVEL_RED, reqLevel)
                end
            end
            local skill, rank, hasReq = GetTrainerServiceSkillReq(id)
            if skill then
                if hasReq then
                    requirements = requirements .. separator .. format(TRAINER_REQ_SKILL_RANK, skill, rank)
                else
                    requirements = requirements .. separator .. format(TRAINER_REQ_SKILL_RANK_RED, skill, rank)
                end
                separator = ", "
            end
            local numReq = GetTrainerServiceNumAbilityReq(id)
            for i = 1, numReq do
                local ability, abilityHas = GetTrainerServiceAbilityReq(id, i)
                if ability then
                    if abilityHas then
                        requirements = requirements .. separator .. format(TRAINER_REQ_ABILITY, ability)
                    else
                        requirements = requirements .. separator .. format(TRAINER_REQ_ABILITY_RED, ability)
                    end
                    separator = ", "
                end
            end
            if requirements ~= "" then
                getglobal("BenillaTrainerSkillRequirements"):SetText(REQUIRES_LABEL .. " " .. requirements)
            else
                getglobal("BenillaTrainerSkillRequirements"):SetText("")
            end

            -- ref Blizzard_TrainerUI.lua (the "Money Frame and cost" block), in full (1937): a free
            -- service hides the frame AND the label and pulls the description up to the label's TOPLEFT;
            -- a costed one shows both, seats the description under the label, and tints the frame white
            -- when the purse covers it, red when not. The frame is repainted either way.
            local moneyCost = GetTrainerServiceCost(id)
            local costFrame = getglobal("ClassTrainerDetailMoneyFrame")
            local costLabel = getglobal("BenillaTrainerCostLabel")
            local description = getglobal("BenillaTrainerSkillDescription")
            if moneyCost and moneyCost > 0 then
                costFrame:Show()
                costLabel:Show()
                description:SetPoint("TOPLEFT", costLabel, "BOTTOMLEFT", 0, -10)
                if (GetMoney() or 0) >= moneyCost then
                    SetMoneyFrameColor("ClassTrainerDetailMoneyFrame", 1.0, 1.0, 1.0)
                else
                    SetMoneyFrameColor("ClassTrainerDetailMoneyFrame", 1.0, 0.1, 0.1)
                end
            else
                costFrame:Hide()
                costLabel:Hide()
                description:SetPoint("TOPLEFT", costLabel, "TOPLEFT", 0, 0)
            end
            MoneyFrame_Update("ClassTrainerDetailMoneyFrame", moneyCost or 0)

            getglobal("BenillaTrainerSkillDescription"):SetText(GetTrainerServiceDescription(id))

            -- Train enable (ref): only an available AND affordable service. The talent/profession-point
            -- gate is dropped (talentPts always 0; the profession-confirm is a later refinement).
            local _, _, serviceType = GetTrainerServiceInfo(id)
            local affordable = (GetMoney() or 0) >= (moneyCost or 0)
            if serviceType == "available" and affordable then
                getglobal("BenillaTrainerTrainButton"):Enable()
            else
                getglobal("BenillaTrainerTrainButton"):Disable()
            end
        end

        -- ── The list page ────────────────────────────────────────────────────────────────────────────
        -- Pick the first learnable (available) service, else the first non-header service (ref
        -- ClassTrainer_SelectFirstLearnableSkill — the backport hardcodes index 2, the first service
        -- under the first header; we find it, robust to which group leads / a leading collapsed group).
        local function selectFirstService()
            local n = GetNumTrainerServices()
            for i = 1, n do
                local _, _, serviceType = GetTrainerServiceInfo(i)
                if serviceType == "available" then
                    SelectTrainerService(i)
                    return
                end
            end
            for i = 1, n do
                local _, _, serviceType = GetTrainerServiceInfo(i)
                if serviceType ~= "header" then
                    SelectTrainerService(i)
                    return
                end
            end
        end

        -- Set the collapse-all tab's +/- icon from whether every group is folded (ref
        -- ClassTrainerFrame_Update's numHeaders/notExpanded tail).
        local function updateCollapseAllIcon(numServices)
            local numHeaders, notExpanded = 0, 0
            for i = 1, numServices do
                local name, _, serviceType, isExpanded = GetTrainerServiceInfo(i)
                if name and serviceType == "header" then
                    numHeaders = numHeaders + 1
                    if not isExpanded then notExpanded = notExpanded + 1 end
                end
            end
            local b = getglobal("BenillaTrainerCollapseAllButton")
            if numHeaders > 0 and notExpanded == numHeaders then
                b.collapsed = 1
                b:SetNormalTexture("Interface\\Buttons\\UI-PlusButton-Up")
            else
                b.collapsed = nil
                b:SetNormalTexture("Interface\\Buttons\\UI-MinusButton-Up")
            end
        end

        function BenillaTrainerFrame_Update()
            getglobal("BenillaTrainerGreetingText"):SetText(GetTrainerGreetingText())
            getglobal("ClassTrainerMoneyFrame"):Show() -- ref ClassTrainerFrame_Show; type PLAYER paints itself

            local numServices = GetNumTrainerServices()
            if numServices == 0 then
                getglobal("BenillaTrainerCollapseAllButton"):Disable()
            else
                getglobal("BenillaTrainerCollapseAllButton"):Enable()
            end

            -- The faux-scroll bar reconciles to the row count, then hands back the top-row offset.
            local scrollFrame = getglobal("BenillaTrainerListScrollFrame")
            FauxScrollFrame_Update(scrollFrame, numServices, BENILLA_TRAINER_ROWS, BENILLA_TRAINER_ROW_HEIGHT)
            local skillOffset = FauxScrollFrame_GetOffset(scrollFrame)

            getglobal("BenillaTrainerSkillHighlight"):Hide()

            -- Fill the visible rows (ref ClassTrainerFrame_Update's row loop). Header rows show the skill
            -- line name + a +/- fold; service rows blank the fold, indent the name two spaces, and colour
            -- name+subtext by state (available green / used gray / unavailable red).
            for i = 1, BENILLA_TRAINER_ROWS do
                local button = getglobal("BenillaTrainerService" .. i)
                local index = i + skillOffset
                if index <= numServices then
                    local name, subText, serviceType, isExpanded = GetTrainerServiceInfo(index)
                    if not name then name = UNKNOWN_LABEL end
                    -- Every row is unlocked here and the selected one re-locked below (ref l.183/190).
                    -- The lock is what paints a selected row's name white: the template's
                    -- `<HighlightFont inherits="GameFontHighlight">` instance wins over the state
                    -- colour SetTextColor writes, which reaches the NORMAL instance only. It reaches
                    -- nothing else on a service row — the branch below blanks that row's fold glow.
                    button:UnlockHighlight()
                    if serviceType == "header" then
                        button:SetText(name)
                        button:SetTextColor(NORMAL_FONT_COLOR.r, NORMAL_FONT_COLOR.g, NORMAL_FONT_COLOR.b)
                        button.subtext:SetText("")
                        if isExpanded then
                            button:SetNormalTexture("Interface\\Buttons\\UI-MinusButton-Up")
                        else
                            button:SetNormalTexture("Interface\\Buttons\\UI-PlusButton-Up")
                        end
                        button.foldHighlight:SetTexture("Interface\\Buttons\\UI-PlusButton-Hilight")
                    else
                        button:SetNormalTexture("")
                        button.foldHighlight:SetTexture("")
                        button:SetText("  " .. name)
                        if subText and subText ~= "" then
                            button.subtext:SetText(format(PARENS_TEMPLATE, subText))
                        else
                            button.subtext:SetText("")
                        end
                        -- The rank rides the NAME's right edge, wherever the name ended (ref l.157,
                        -- B253's flow row) — re-anchored every repaint because the name's width is
                        -- the thing that changes.
                        button.subtext:SetPoint("LEFT", getglobal(button:GetName() .. "Text"), "RIGHT", 10, 0)
                        if serviceType == "available" then
                            button:SetTextColor(0, 1.0, 0)
                            button.subR, button.subG, button.subB = 0, 0.6, 0
                        elseif serviceType == "used" then
                            button:SetTextColor(GRAY_FONT_COLOR.r, GRAY_FONT_COLOR.g, GRAY_FONT_COLOR.b)
                            button.subR, button.subG, button.subB = 0.5, 0.5, 0.5
                        else
                            button:SetTextColor(0.9, 0, 0)
                            button.subR, button.subG, button.subB = 0.6, 0, 0
                        end
                        button.subtext:SetTextColor(button.subR, button.subG, button.subB)
                    end
                    button.serviceIndex = index
                    button:Show()
                else
                    button.serviceIndex = nil
                    button:UnlockHighlight()
                    button:SetText("")
                    button.subtext:SetText("")
                    button:SetNormalTexture("")
                    button.foldHighlight:SetTexture("")
                    button:Hide()
                end
            end

            -- Selection highlight + detail (ref l.146-186). The glow rides the selected SERVICE row while
            -- it is inside the visible window; a header selection shows no glow. The detail fills only for
            -- a selected service.
            local selection = GetTrainerSelectionIndex()
            local selType
            if selection >= 1 and selection <= numServices then
                _, _, selType = GetTrainerServiceInfo(selection)
            end
            if selType and selType ~= "header"
                and selection > skillOffset and selection <= skillOffset + BENILLA_TRAINER_ROWS then
                local selButton = getglobal("BenillaTrainerService" .. (selection - skillOffset))
                local hl = getglobal("BenillaTrainerSkillHighlight")
                local tex = getglobal("BenillaTrainerSkillHighlightTexture")
                if selType == "available" then
                    tex:SetVertexColor(0, 1.0, 0)
                elseif selType == "used" then
                    tex:SetVertexColor(0.5, 0.5, 0.5)
                else
                    tex:SetVertexColor(0.9, 0, 0)
                end
                hl:SetPoint("TOPLEFT", selButton, "TOPLEFT", 0, 0)
                hl:Show()
                -- The whole selected row goes white, and it is the ref's own pair of moves (l.183-184):
                -- LockHighlight for the NAME (the button's label, so the white comes from its
                -- HighlightFont instance, not from a repaint that the next Update would undo) and an
                -- explicit whiten for the SUBTEXT, which is a child FontString the lock cannot reach.
                -- An earlier revision called the white name a deliberate divergence "the ref does not
                -- do"; the ref does it, through the lock this window had no engine method for at the
                -- time (decision 1605). subR/subG/subB go white too so a hover-then-leave keeps the
                -- subtext white.
                selButton:LockHighlight()
                selButton.subtext:SetTextColor(HIGHLIGHT_FONT_COLOR.r, HIGHLIGHT_FONT_COLOR.g, HIGHLIGHT_FONT_COLOR.b)
                selButton.subR, selButton.subG, selButton.subB =
                    HIGHLIGHT_FONT_COLOR.r, HIGHLIGHT_FONT_COLOR.g, HIGHLIGHT_FONT_COLOR.b
            end

            if selType and selType ~= "header" then
                BenillaTrainer_ShowDetails(selection)
            else
                BenillaTrainer_HideDetails()
            end

            updateCollapseAllIcon(numServices)
        end

        -- The window's wheel handler (bubbled up the parent chain from a row) → one row via the faux kit.
        function BenillaTrainerFrame_OnMouseWheel(delta)
            BenillaFauxScrollFrame_OnMouseWheel(getglobal("BenillaTrainerListScrollFrame"), delta)
        end

        -- A row click: a header folds/unfolds its group (Collapse/ExpandTrainerSkillLine take the header's
        -- display index); a service selects (ref ClassTrainerSkillButton_OnClick + SetSelection's header
        -- branch). Left-button only.
        function BenillaTrainerSkillButton_OnClick(button, mouseButton)
            if mouseButton ~= "LeftButton" then return end
            local index = button.serviceIndex
            if not index then return end
            local _, _, serviceType, isExpanded = GetTrainerServiceInfo(index)
            if serviceType == "header" then
                if isExpanded then
                    CollapseTrainerSkillLine(index)
                else
                    ExpandTrainerSkillLine(index)
                end
            else
                SelectTrainerService(index)
            end
            BenillaTrainerFrame_Update()
        end

        -- Hover recolors a service row's subtext to HIGHLIGHT, restoring its state colour on leave (ref
        -- ClassTrainerSkillButton_OnEnter/OnLeave). Harmless over a header (its subtext is blank).
        function BenillaTrainerSkillButton_OnEnter(button)
            button.subtext:SetTextColor(HIGHLIGHT_FONT_COLOR.r, HIGHLIGHT_FONT_COLOR.g, HIGHLIGHT_FONT_COLOR.b)
        end

        function BenillaTrainerSkillButton_OnLeave(button)
            button.subtext:SetTextColor(button.subR or 0.5, button.subG or 0.5, button.subB or 0.5)
        end

        -- ── The Train button ─────────────────────────────────────────────────────────────────────────
        -- Buy the selected service, then repaint (the row flips to "used" once the app pushes the fresh
        -- snapshot). The tradeskill profession-confirm dialog is a later refinement.
        function BenillaTrainerTrainButton_OnClick()
            BuyTrainerService(GetTrainerSelectionIndex())
            BenillaTrainerFrame_Update()
        end

        -- ── The state-filter dropdown (ref ClassTrainerFrameFilterDropDown_*) ────────────────────────
        function BenillaTrainerFilterDropDown_OnLoad()
            UIDropDownMenu_Initialize(BenillaTrainerFilterDropDown, BenillaTrainerFilterDropDown_Initialize)
            UIDropDownMenu_SetText(FILTER_LABEL, BenillaTrainerFilterDropDown)
            UIDropDownMenu_SetWidth(96, BenillaTrainerFilterDropDown)
        end

        function BenillaTrainerFilterDropDown_Initialize()
            local function addRow(kind, label, code)
                local info = {}
                info.text = code .. label .. CODE_CLOSE
                info.value = kind
                info.func = BenillaTrainerFilterDropDown_OnClick
                info.checked = GetTrainerServiceTypeFilter(kind) and 1 or nil
                info.keepShownOnClick = 1
                UIDropDownMenu_AddButton(info)
            end
            addRow("available", LABEL_AVAILABLE, GREEN_CODE)
            addRow("unavailable", LABEL_UNAVAILABLE, RED_CODE)
            addRow("used", LABEL_USED, GRAY_CODE)
        end

        -- A row's func fires with the row button as `this`, carrying the PRE-click state (this.value /
        -- this.checked): the kit's UIDropDownMenuButton_OnClick runs the func FIRST and only then, for a
        -- keepShownOnClick row, flips the check texture + this.checked itself. So the func's whole job is
        -- to flip the ENGINE filter to the inverse of the pre-click check, reset scroll, and repaint —
        -- the visible check is the kit's to move, and the next open re-derives every row from
        -- GetTrainerServiceTypeFilter anyway.
        --
        -- It must NOT re-Initialize the open menu here. Doing so re-ran AddButton, which sets
        -- `button.checked` (and the Check texture) from the fresh engine state — so the kit's flip
        -- immediately afterwards inverted the ALREADY-correct row and put it back. The check never
        -- appeared to move, and because `this.checked` then read stale-true forever, a filter switched
        -- off could never be switched back on.
        function BenillaTrainerFilterDropDown_OnClick()
            -- The engine filter AND the saved global, together: the global is what survives the
            -- restart and what BenillaTrainerFrame_ApplyFilter pushes back after the per-packet
            -- reset, so writing only the engine would lose the toggle at the next list (the ref's
            -- own setglobal pair, Blizzard_TrainerUI.lua:526-530).
            local on = 0
            if not this.checked then
                on = 1
            end
            setglobal("TRAINER_FILTER_" .. strupper(this.value), on)
            SetTrainerServiceTypeFilter(this.value, on)
            FauxScrollFrame_SetOffset(getglobal("BenillaTrainerListScrollFrame"), 0)
            BenillaTrainerFrame_Update()
        end

        -- ── The collapse-all tab ─────────────────────────────────────────────────────────────────────
        -- Fold / unfold every group (Collapse/ExpandTrainerSkillLine(0), ref
        -- ClassTrainerCollapseAllButton_OnClick).
        function BenillaTrainerCollapseAllButton_OnClick()
            local b = getglobal("BenillaTrainerCollapseAllButton")
            if b.collapsed then
                b.collapsed = nil
                ExpandTrainerSkillLine(0)
            else
                b.collapsed = 1
                FauxScrollFrame_SetOffset(getglobal("BenillaTrainerListScrollFrame"), 0)
                CollapseTrainerSkillLine(0)
            end
            BenillaTrainerFrame_Update()
        end

        -- ── The NPC-session lifecycle (MerchantFrame.xml's own shape) ────────────────────────────────
        function BenillaTrainerFrame_OnLoad(frame)
            -- The NPC portrait: the "npc" unit token → the trainer's live model bake
            -- (crates/benilla/src/portrait, InteractNpc) — MerchantFrame's own binding.
            SetPortraitTexture(getglobal(frame:GetName() .. "Portrait"), "npc")
            frame:RegisterEvent("TRAINER_SHOW")
            frame:RegisterEvent("TRAINER_UPDATE")
            frame:RegisterEvent("TRAINER_CLOSED")
            frame:RegisterEvent("PLAYER_MONEY")
            -- The list repaint is wired in the scroll frame's own `<OnVerticalScroll>` below, the
            -- reference's way; `updateFunc` was our kit's field and the reference has none (1860).
        end

        -- Push the three saved globals into the engine — the ref's ClassTrainerFrame <OnShow>
        -- (Blizzard_TrainerUI.xml:531-533), and it is NOT redundant: the list builder rewrites the
        -- engine's filter mask to its own default on every SMSG_TRAINER_LIST (byte-verified,
        -- `0x4d75d9 mov ds:0xb73a1c,3`; decision 1128), so this is what puts the player's remembered
        -- choice back. Called on show and at the top of TRAINER_SHOW — our repaint runs before
        -- ShowUIPanel, so applying it only in OnShow would leave one frame painted under the reset.
        function BenillaTrainerFrame_ApplyFilter()
            SetTrainerServiceTypeFilter("available", TRAINER_FILTER_AVAILABLE)
            SetTrainerServiceTypeFilter("unavailable", TRAINER_FILTER_UNAVAILABLE)
            SetTrainerServiceTypeFilter("used", TRAINER_FILTER_USED)
        end

        -- The scroll frame's `<OnVerticalScroll>` lives in its own chunk and cannot see this
        -- file's `local BENILLA_TRAINER_ROW_HEIGHT`, so the pitch is handed over here rather than
        -- written as a literal in the XML (1860). The reference has the same shape with globals:
        -- `QUESTLOG_QUEST_HEIGHT` and friends are file-scope globals in its own FrameXML.
        function BenillaTrainerList_OnVerticalScroll()
            FauxScrollFrame_OnVerticalScroll(BENILLA_TRAINER_ROW_HEIGHT, BenillaTrainerFrame_Update)
        end

        function BenillaTrainerFrame_SetTitle(name)
            if name and name ~= "" then
                getglobal("BenillaTrainerTitleText"):SetText(name)
            else
                getglobal("BenillaTrainerTitleText"):SetText("Trainer")
            end
        end

        function BenillaTrainerFrame_OnEvent(frame)
            if event == "TRAINER_SHOW" then
                -- SHOW FIRST, then populate — the reference's own order, and not a style choice.
                -- `FauxScrollFrame_Update` (the chain's since 1837) gates everything that sets the
                -- bar's range on `frame:IsVisible()`, so a list repainted before its window is up
                -- leaves `SetMinMaxValues` unset and both arrows dead. The reference relies on this
                -- order hard enough to test it: `MerchantFrame.lua:22-27` does `ShowUIPanel(this)`
                -- and then treats `not this:IsVisible()` as the panel system refusing, and closes.
                -- Decision 1860.
                ShowUIPanel(frame)
                -- Fresh session: top of the list, a first selection (ref ClassTrainerFrame_Show).
                BenillaTrainerFrame_ApplyFilter()
                BenillaTrainerFrame_SetTitle(arg1)
                FauxScrollFrame_SetOffset(getglobal("BenillaTrainerListScrollFrame"), 0)
                if GetTrainerSelectionIndex() == 0 then
                    selectFirstService()
                end
                BenillaTrainerFrame_Update()
            elseif event == "TRAINER_UPDATE" then
                BenillaTrainerFrame_SetTitle(arg1)
                -- Re-anchor the selection if it fell off the (possibly shorter) list.
                if GetTrainerSelectionIndex() == 0 then
                    selectFirstService()
                end
                BenillaTrainerFrame_Update()
            elseif event == "TRAINER_CLOSED" then
                HideUIPanel(frame)
            elseif event == "PLAYER_MONEY" then
                -- A buy changes affordability without a TRAINER_UPDATE — repaint the detail's cost tint.
                if BenillaTrainerFrame:IsVisible() then
                    BenillaTrainerFrame_Update()
                end
            end
        end

        function BenillaTrainerCloseButton_OnClick()
            CloseTrainer()
            HideUIPanel(getglobal("BenillaTrainerFrame"))
        end
    ]]></Script>

    <!--
        One row (ref ClassTrainerSkillButtonTemplate): a 293×16 text row — the +/- fold slot at the left
        (used for header rows, blanked per-row for services), the name, and the rank subtext beside it.
        NO item icon (the list rows carry none; the spell icon is the DETAIL pane's). <OnLoad> wires the
        child regions + the fold highlight onto `self` (the QuestLogFrame.xml row-template shape).

        THE ROW IS A FLOW, NOT TWO COLUMNS (B253). The name carries **no width**, so it never wraps:
        a FontString given an explicit width wraps at it, and a 16px row cannot grow — which is how
        "Handstitched Leather Pants" came to draw two lines over the row beneath it. The reference's
        own row (`ClassTrainerFrameTemplates.xml`, read off the player's chain, never transcribed)
        makes the name the Button's `<ButtonText>` at width **0** and then SetPoints the subtext to
        that text's RIGHT + 10 from Lua, per row — so a long name simply runs on and pushes its
        "(Rank N)" along. We express the same law declaratively: no size on either string, the
        subtext anchored to the name's right edge. The 160/188 fixed columns this replaces were
        benilla's invention, and both halves of them were wrong — the cap wrapped, and the column
        put the rank at a fixed x the reference never uses.
    -->
    <Button name="BenillaTrainerServiceTemplate" virtual="true" hidden="true">
        <Size><AbsDimension x="293" y="16"/></Size>
        <Layers>
            <Layer level="ARTWORK">
                <!-- NO <Anchors> — Update SetPoints this to the row's own label every repaint, the
                     ref's own move (`skillSubText:SetPoint("LEFT", <row>Text, "RIGHT", 10, 0)`,
                     Blizzard_TrainerUI.lua l.157). A `relativeTo="$parentText"` here CANNOT work and
                     fails quietly: `<Layers>` is loader step 5 and the `<ButtonText>` is step 5b, so
                     the label does not exist yet and the anchor falls back to the row (the loader
                     does warn — `resolve_target`'s "does not resolve" line). The ref anchors it at
                     runtime for its own reason anyway: the rank must follow a name whose width is
                     only known once the name is measured (B253). -->
                <FontString name="$parentSubText" inherits="GameFontNormalSmall" justifyH="LEFT"/>
            </Layer>
        </Layers>
        <!-- THE SERVICE NAME IS THE BUTTON'S OWN ButtonText (the ref's `ClassTrainerSkill<n>Text`),
             under the base's font TRIO — that is what turns a row white under the cursor and holds
             the selected row white, with no script involved: `GameFontHighlight` is white, the engine
             swaps the highlighted font instance in on hover, and `LockHighlight()` pins it for the
             selection. It was a `$parentName` FontString until decision 1605, on a stale note that
             `Button:SetTextColor`/`LockHighlight` had no engine method. Carries NO `<Size>` — B253's
             flow row: the name measures to its own text and `$parentSubText` follows its right edge,
             which is the reference's own `<ButtonText>`-at-width-0 plus per-row
             `SetPoint("LEFT", <row>Text, "RIGHT", 10, 0)`. TradeSkillFrame.xml and CraftFrame.xml are
             the twins (both fixed-column, so both keep an explicit width). -->
        <ButtonText name="$parentText" justifyH="LEFT">
            <Anchors><Anchor point="LEFT" relativePoint="LEFT"><Offset><AbsDimension x="22" y="0"/></Offset></Anchor></Anchors>
        </ButtonText>
        <NormalFont inherits="GameFontNormal" justifyH="LEFT"/>
        <HighlightFont inherits="GameFontHighlight" justifyH="LEFT"/>
        <DisabledFont inherits="GameFontDisable" justifyH="LEFT"/>
        <!-- The +/- fold slot + its hover glow: meaningful for header rows (Update sets +/- there),
             blanked for services. -->
        <NormalTexture file="Interface\Buttons\UI-MinusButton-UP">
            <Size><AbsDimension x="16" y="16"/></Size>
            <Anchors><Anchor point="LEFT" relativePoint="LEFT"><Offset><AbsDimension x="3" y="0"/></Offset></Anchor></Anchors>
        </NormalTexture>
        <HighlightTexture name="$parentHighlight" file="Interface\Buttons\UI-PlusButton-Hilight" alphaMode="ADD">
            <Size><AbsDimension x="16" y="16"/></Size>
            <Anchors><Anchor point="LEFT" relativePoint="LEFT"><Offset><AbsDimension x="3" y="0"/></Offset></Anchor></Anchors>
        </HighlightTexture>
        <Scripts>
            <OnLoad>
                self.subtext = getglobal(self:GetName() .. "SubText")
                self.foldHighlight = self:GetHighlightTexture()
            </OnLoad>
            <OnClick>BenillaTrainerSkillButton_OnClick(self, arg1)</OnClick>
            <OnEnter>BenillaTrainerSkillButton_OnEnter(self)</OnEnter>
            <OnLeave>BenillaTrainerSkillButton_OnLeave(self)</OnLeave>
        </Scripts>
    </Button>

    <!-- A panel action button (Train/Exit): the UIPanelButtonTemplate face, label via text=. -->
    <Button name="BenillaTrainerPanelButtonTemplate" virtual="true">
        <Size><AbsDimension x="80" y="22"/></Size>
        <NormalFont inherits="GameFontNormal"/>
        <HighlightFont inherits="GameFontHighlight"/>
        <DisabledFont inherits="GameFontDisable"/>
        <NormalTexture file="Interface\Buttons\UI-Panel-Button-Up"><TexCoords left="0" right="0.625" top="0" bottom="0.6875"/></NormalTexture>
        <PushedTexture file="Interface\Buttons\UI-Panel-Button-Down"><TexCoords left="0" right="0.625" top="0" bottom="0.6875"/></PushedTexture>
        <DisabledTexture file="Interface\Buttons\UI-Panel-Button-Disabled"><TexCoords left="0" right="0.625" top="0" bottom="0.6875"/></DisabledTexture>
        <HighlightTexture file="Interface\Buttons\UI-Panel-Button-Highlight" alphaMode="ADD"><TexCoords left="0" right="0.625" top="0" bottom="0.6875"/></HighlightTexture>
    </Button>

    <Frame name="BenillaTrainerFrame" hidden="true">
        <!-- The real 384×512 window. No <Anchors> — ShowUIPanel SetPoints this to the left slot. -->
        <Size><AbsDimension x="384" y="512"/></Size>
        <Layers>
            <!-- NPC portrait 60×60 TOPLEFT (7,-6) (ref), BACKGROUND so the window art's ring frames it.
                 Bound in OnLoad via SetPortraitTexture(region, "npc") — the trainer's live model bake. -->
            <Layer level="BACKGROUND">
                <Texture name="$parentPortrait">
                    <Size><AbsDimension x="60" y="60"/></Size>
                    <Anchors><Anchor point="TOPLEFT" relativePoint="TOPLEFT"><Offset><AbsDimension x="7" y="-6"/></Offset></Anchor></Anchors>
                </Texture>
            </Layer>
            <!-- The four quadrant slabs that ARE the window art (ref): 256-wide left halves, 128-wide
                 right halves, each 256 tall, pinned to their corner, whole-texture. -->
            <Layer level="BORDER">
                <Texture file="Interface\ClassTrainerFrame\UI-ClassTrainer-TopLeft"><Size><AbsDimension x="256" y="256"/></Size><Anchors><Anchor point="TOPLEFT" relativePoint="TOPLEFT"/></Anchors></Texture>
                <Texture file="Interface\ClassTrainerFrame\UI-ClassTrainer-TopRight"><Size><AbsDimension x="128" y="256"/></Size><Anchors><Anchor point="TOPRIGHT" relativePoint="TOPRIGHT"/></Anchors></Texture>
                <Texture file="Interface\ClassTrainerFrame\UI-ClassTrainer-BotLeft"><Size><AbsDimension x="256" y="256"/></Size><Anchors><Anchor point="BOTTOMLEFT" relativePoint="BOTTOMLEFT"/></Anchors></Texture>
                <Texture file="Interface\ClassTrainerFrame\UI-ClassTrainer-BotRight"><Size><AbsDimension x="128" y="256"/></Size><Anchors><Anchor point="BOTTOMRIGHT" relativePoint="BOTTOMRIGHT"/></Anchors></Texture>
                <!-- Title: the NPC's name, fed as arg1 of TRAINER_SHOW/UPDATE via the NameCache; the
                     static "Trainer" shows until the creature-name query lands. -->
                <FontString name="BenillaTrainerTitleText" inherits="GameFontNormal" justifyH="CENTER" text="Trainer">
                    <Anchors><Anchor point="TOP" relativePoint="TOP"><Offset><AbsDimension x="0" y="-17"/></Offset></Anchor></Anchors>
                </FontString>
                <!-- Greeting (GetTrainerGreetingText), GameFontHighlight LEFT/TOP, 260×26, TOPLEFT (76,-38). -->
                <FontString name="BenillaTrainerGreetingText" inherits="GameFontHighlight" justifyH="LEFT" justifyV="TOP">
                    <Size><AbsDimension x="260" y="26"/></Size>
                    <Anchors><Anchor point="TOPLEFT" relativePoint="TOPLEFT"><Offset><AbsDimension x="76" y="-38"/></Offset></Anchor></Anchors>
                </FontString>
            </Layer>
            <!-- The horizontal divider between the list and the detail pane (ref): 256+75 wide, 16 tall,
                 TOPLEFT (15,-275), sampled from UI-ClassTrainer-HorizontalBar by TexCoord. -->
            <Layer level="ARTWORK">
                <Texture name="BenillaTrainerHorizontalBar" file="Interface\ClassTrainerFrame\UI-ClassTrainer-HorizontalBar">
                    <Size><AbsDimension x="256" y="16"/></Size>
                    <Anchors><Anchor point="TOPLEFT" relativePoint="TOPLEFT"><Offset><AbsDimension x="15" y="-275"/></Offset></Anchor></Anchors>
                    <TexCoords left="0" right="1.0" top="0" bottom="0.25"/>
                </Texture>
                <Texture file="Interface\ClassTrainerFrame\UI-ClassTrainer-HorizontalBar">
                    <Size><AbsDimension x="75" y="16"/></Size>
                    <Anchors><Anchor point="LEFT" relativeTo="BenillaTrainerHorizontalBar" relativePoint="RIGHT"/></Anchors>
                    <TexCoords left="0" right="0.29296875" top="0.25" bottom="0.5"/>
                </Texture>
            </Layer>
            <!-- The FIXED detail-pane FontStrings (ref DetailScrollChildFrame), flattened onto this
                 window's own Layers (the flat-layout gap). Blanked/filled by Hide/ShowDetails.

                 THE WIDTHS ARE THE REFERENCE'S, not ours (B253). A FontString wraps at whatever
                 width it is given, so an invented narrow one is a wrap bug waiting for a long name:
                 the detail name at 150 broke "Handstitched Leather Pants" over two lines. The
                 reference's detail child is 296 wide with its name/requirements at **244** and its
                 description at **290**; our flattened anchors put the name at the same window x (68)
                 the child's 46 resolves to, so the same numbers land in the same place — and, unlike
                 the 290/300 they replace, they stay inside the pane instead of running past its
                 right edge at 358/330. -->
            <Layer level="OVERLAY">
                <FontString name="BenillaTrainerSkillName" inherits="GameFontNormal" justifyH="LEFT">
                    <Size><AbsDimension x="244" y="0"/></Size>
                    <Anchors><Anchor point="TOPLEFT" relativePoint="TOPLEFT"><Offset><AbsDimension x="68" y="-293"/></Offset></Anchor></Anchors>
                </FontString>
                <FontString name="BenillaTrainerSkillRequirements" inherits="GameFontHighlightSmall" justifyH="LEFT">
                    <Size><AbsDimension x="244" y="0"/></Size>
                    <Anchors><Anchor point="TOPLEFT" relativeTo="BenillaTrainerSkillName" relativePoint="BOTTOMLEFT"><Offset><AbsDimension x="0" y="-4"/></Offset></Anchor></Anchors>
                </FontString>
                <FontString name="BenillaTrainerCostLabel" inherits="GameFontNormalSmall" justifyH="LEFT" text="COSTS_LABEL">
                    <Anchors><Anchor point="TOPLEFT" relativePoint="TOPLEFT"><Offset><AbsDimension x="30" y="-340"/></Offset></Anchor></Anchors>
                </FontString>
                <FontString name="BenillaTrainerSkillDescription" inherits="GameFontHighlightSmall" justifyH="LEFT">
                    <Size><AbsDimension x="290" y="0"/></Size>
                    <Anchors><Anchor point="TOPLEFT" relativeTo="BenillaTrainerCostLabel" relativePoint="BOTTOMLEFT"><Offset><AbsDimension x="0" y="-10"/></Offset></Anchor></Anchors>
                </FontString>
            </Layer>
        </Layers>
        <Frames>
            <!-- The top-right close X (ref a UIPanelCloseButton at TOPRIGHT (-29,-8); the minimize-button
                 art stands in). -->
            <Button name="BenillaTrainerCloseButton">
                <Size><AbsDimension x="32" y="32"/></Size>
                <Anchors><Anchor point="TOPRIGHT" relativePoint="TOPRIGHT"><Offset><AbsDimension x="-29" y="-8"/></Offset></Anchor></Anchors>
                <NormalTexture file="Interface\Buttons\UI-Panel-MinimizeButton-Up"/>
                <PushedTexture file="Interface\Buttons\UI-Panel-MinimizeButton-Down"/>
                <HighlightTexture file="Interface\Buttons\UI-Panel-MinimizeButton-Highlight" alphaMode="ADD"/>
                <Scripts><OnClick>BenillaTrainerCloseButton_OnClick()</OnClick></Scripts>
            </Button>

            <!-- The expand/collapse-all tab (ref ClassTrainerExpandButtonFrame): a tab-shaped frame
                 carrying the collapse-all button — now functional (Collapse/ExpandTrainerSkillLine(0)). -->
            <Frame name="BenillaTrainerExpandButtonFrame">
                <Size><AbsDimension x="54" y="32"/></Size>
                <Anchors><Anchor point="TOPLEFT" relativePoint="TOPLEFT"><Offset><AbsDimension x="15" y="-70"/></Offset></Anchor></Anchors>
                <Layers><Layer level="BACKGROUND">
                    <Texture name="BenillaTrainerExpandTabLeft" file="Interface\ClassTrainerFrame\UI-ClassTrainer-ExpandTab-Left"><Size><AbsDimension x="8" y="32"/></Size><Anchors><Anchor point="TOPLEFT" relativePoint="TOPLEFT"/></Anchors></Texture>
                    <Texture name="BenillaTrainerExpandTabMiddle" file="Interface\QuestFrame\UI-QuestLogSortTab-Middle"><Size><AbsDimension x="38" y="32"/></Size><Anchors><Anchor point="LEFT" relativeTo="BenillaTrainerExpandTabLeft" relativePoint="RIGHT"><Offset><AbsDimension x="0" y="6"/></Offset></Anchor></Anchors></Texture>
                    <Texture file="Interface\QuestFrame\UI-QuestLogSortTab-Right"><Size><AbsDimension x="8" y="32"/></Size><Anchors><Anchor point="LEFT" relativeTo="BenillaTrainerExpandTabMiddle" relativePoint="RIGHT"/></Anchors></Texture>
                </Layer></Layers>
                <Frames>
                    <Button name="BenillaTrainerCollapseAllButton" text="All">
                        <Size><AbsDimension x="40" y="22"/></Size>
                        <Anchors><Anchor point="LEFT" relativeTo="BenillaTrainerExpandTabLeft" relativePoint="RIGHT"><Offset><AbsDimension x="0" y="3"/></Offset></Anchor></Anchors>
                        <NormalTexture file="Interface\Buttons\UI-MinusButton-Up"><Size><AbsDimension x="16" y="16"/></Size><Anchors><Anchor point="LEFT" relativePoint="LEFT"/></Anchors></NormalTexture>
                        <HighlightTexture file="Interface\Buttons\UI-PlusButton-Hilight" alphaMode="ADD"><Size><AbsDimension x="16" y="16"/></Size><Anchors><Anchor point="LEFT" relativePoint="LEFT"/></Anchors></HighlightTexture>
                        <ButtonText><Anchors><Anchor point="LEFT" relativePoint="LEFT"><Offset><AbsDimension x="18" y="0"/></Offset></Anchor></Anchors></ButtonText>
                        <NormalFont inherits="GameFontNormalSmall" justifyH="LEFT"/>
                        <Scripts><OnClick>BenillaTrainerCollapseAllButton_OnClick()</OnClick></Scripts>
                    </Button>
                </Frames>
            </Frame>

            <!-- The state-filter dropdown (ref ClassTrainerFrameFilterDropDown): the UIDropDownMenu capsule
                 whose three keepShownOnClick check rows drive the engine's state-visibility filter —
                 replacing the three inline sort checkboxes. TOPRIGHT (-26,-64), the ref's spot. -->
            <Frame name="BenillaTrainerFilterDropDown" inherits="UIDropDownMenuTemplate">
                <Anchors><Anchor point="TOPRIGHT" relativePoint="TOPRIGHT"><Offset><AbsDimension x="-26" y="-64"/></Offset></Anchor></Anchors>
                <Scripts>
                    <OnLoad>BenillaTrainerFilterDropDown_OnLoad()</OnLoad>
                    <OnShow>BenillaTrainerFilterDropDown_OnLoad()</OnShow>
                </Scripts>
            </Frame>

            <!-- The persistent selection highlight (ref ClassTrainerSkillHighlightFrame): 293×16,
                 ARTWORK-layer UI-Listbox-Highlight2. Declared BEFORE the rows so the row text paints OVER
                 the glow (same parent + level ⇒ declaration order is the z-tiebreak). Moved onto the
                 selected visible service row + vertex-colored by state. -->
            <Frame name="BenillaTrainerSkillHighlight" hidden="true">
                <Size><AbsDimension x="293" y="16"/></Size>
                <Anchors><Anchor point="TOPLEFT" relativePoint="TOPLEFT"/></Anchors>
                <Layers><Layer level="ARTWORK">
                    <Texture name="BenillaTrainerSkillHighlightTexture" file="Interface\Buttons\UI-Listbox-Highlight2">
                        <Anchors><Anchor point="TOPLEFT"/><Anchor point="BOTTOMRIGHT"/></Anchors>
                    </Texture>
                </Layer></Layers>
            </Frame>

            <!-- 11 tree rows (ref ClassTrainerSkill1..11): 293×16, row1 TOPLEFT (22,-100); rows 2-11 chain
                 TOPLEFT→prior BOTTOMLEFT with no gap. -->
            <Button name="BenillaTrainerService1" inherits="BenillaTrainerServiceTemplate">
                <Anchors><Anchor point="TOPLEFT" relativePoint="TOPLEFT"><Offset><AbsDimension x="22" y="-100"/></Offset></Anchor></Anchors>
            </Button>
            <Button name="BenillaTrainerService2" inherits="BenillaTrainerServiceTemplate"><Anchors><Anchor point="TOPLEFT" relativeTo="BenillaTrainerService1" relativePoint="BOTTOMLEFT"/></Anchors></Button>
            <Button name="BenillaTrainerService3" inherits="BenillaTrainerServiceTemplate"><Anchors><Anchor point="TOPLEFT" relativeTo="BenillaTrainerService2" relativePoint="BOTTOMLEFT"/></Anchors></Button>
            <Button name="BenillaTrainerService4" inherits="BenillaTrainerServiceTemplate"><Anchors><Anchor point="TOPLEFT" relativeTo="BenillaTrainerService3" relativePoint="BOTTOMLEFT"/></Anchors></Button>
            <Button name="BenillaTrainerService5" inherits="BenillaTrainerServiceTemplate"><Anchors><Anchor point="TOPLEFT" relativeTo="BenillaTrainerService4" relativePoint="BOTTOMLEFT"/></Anchors></Button>
            <Button name="BenillaTrainerService6" inherits="BenillaTrainerServiceTemplate"><Anchors><Anchor point="TOPLEFT" relativeTo="BenillaTrainerService5" relativePoint="BOTTOMLEFT"/></Anchors></Button>
            <Button name="BenillaTrainerService7" inherits="BenillaTrainerServiceTemplate"><Anchors><Anchor point="TOPLEFT" relativeTo="BenillaTrainerService6" relativePoint="BOTTOMLEFT"/></Anchors></Button>
            <Button name="BenillaTrainerService8" inherits="BenillaTrainerServiceTemplate"><Anchors><Anchor point="TOPLEFT" relativeTo="BenillaTrainerService7" relativePoint="BOTTOMLEFT"/></Anchors></Button>
            <Button name="BenillaTrainerService9" inherits="BenillaTrainerServiceTemplate"><Anchors><Anchor point="TOPLEFT" relativeTo="BenillaTrainerService8" relativePoint="BOTTOMLEFT"/></Anchors></Button>
            <Button name="BenillaTrainerService10" inherits="BenillaTrainerServiceTemplate"><Anchors><Anchor point="TOPLEFT" relativeTo="BenillaTrainerService9" relativePoint="BOTTOMLEFT"/></Anchors></Button>
            <Button name="BenillaTrainerService11" inherits="BenillaTrainerServiceTemplate"><Anchors><Anchor point="TOPLEFT" relativeTo="BenillaTrainerService10" relativePoint="BOTTOMLEFT"/></Anchors></Button>

            <!-- The faux-scroll frame (`FauxScrollFrameTemplate`, the REFERENCE's since 1837):
                 invisible container over the 11 rows; only its right-hand Slider scroll bar renders.
                 Sized to the 11-row span so the bar sits in the window's right gutter.

                 THE OWNER DECLARES `<OnVerticalScroll>`, which is how the reference's kit works and
                 the one thing our transcription did differently: ours carried a `frame.updateFunc`
                 field that `BenillaFauxScrollBar_OnValueChanged` read, and the reference has no such
                 field. Its chain is the bar's own OnValueChanged
                 (`this:GetParent():SetVerticalScroll(arg1)`, UIPanelTemplates.xml) -> this handler ->
                 `FauxScrollFrame_OnVerticalScroll(itemHeight, updateFunction)`, which is the only
                 thing that writes `frame.offset`. Without it the arrows and the thumb move the bar
                 and the list never follows (1860). 16 is the row pitch
                 (`BenillaTrainerServiceTemplate`). -->
            <ScrollFrame name="BenillaTrainerListScrollFrame" inherits="FauxScrollFrameTemplate">
                <Size><AbsDimension x="293" y="176"/></Size>
                <Anchors><Anchor point="TOPLEFT" relativePoint="TOPLEFT"><Offset><AbsDimension x="22" y="-100"/></Offset></Anchor></Anchors>
                <Scripts>
                    <OnVerticalScroll>BenillaTrainerList_OnVerticalScroll()</OnVerticalScroll>
                </Scripts>
            </ScrollFrame>

            <!-- The detail spell icon (ref ClassTrainerSkillIcon): a 37×37 button over a 64×64 UI-EmptySlot
                 ring, at the detail area's top-left. Icon via SetNormalTexture; Hide()n when unselected.

                 The hover is the ref's own, verbatim (Blizzard_TrainerUI.xml:452-459): owner is the icon
                 button, anchor ANCHOR_RIGHT, subject `ClassTrainerFrame.selectedService` — the SELECTED
                 row, which is why the tooltip describes the selection no matter which row the mouse
                 passed over on its way here. GetTrainerSelectionIndex() is our engine-held equivalent of
                 that field; it reads 0 with nothing selected, and SetTrainerService no-ops on 0. This is
                 the ONLY SetTrainerService call site in the shipped client — the list rows carry no
                 tooltip of their own (their template's OnEnter only recolours the subtext). -->
            <Button name="BenillaTrainerSkillIcon" hidden="true">
                <Size><AbsDimension x="37" y="37"/></Size>
                <Anchors><Anchor point="TOPLEFT" relativePoint="TOPLEFT"><Offset><AbsDimension x="26" y="-291"/></Offset></Anchor></Anchors>
                <Layers><Layer level="BACKGROUND">
                    <Texture file="Interface\Buttons\UI-EmptySlot"><Size><AbsDimension x="64" y="64"/></Size><Anchors><Anchor point="TOPLEFT" relativePoint="TOPLEFT"><Offset><AbsDimension x="-13" y="13"/></Offset></Anchor></Anchors></Texture>
                </Layer></Layers>
                <Scripts>
                    <OnEnter>
                        GameTooltip:SetOwner(self, "ANCHOR_RIGHT")
                        GameTooltip:SetTrainerService(GetTrainerSelectionIndex())
                        GameTooltip:Show()
                    </OnEnter>
                    <OnLeave>GameTooltip:Hide()</OnLeave>
                </Scripts>
            </Button>

            <!-- ref Blizzard_TrainerUI.xml:463-476, and the reference's own NAME: the cost, a
                 SmallMoneyFrameTemplate of type STATIC at the same LEFT->cost-label RIGHT (5,0) seat,
                 painted by MoneyFrame_Update on every detail refresh. Retires the detail coin trio (1937). -->
            <Frame name="ClassTrainerDetailMoneyFrame" inherits="SmallMoneyFrameTemplate">
                <Anchors><Anchor point="LEFT" relativeTo="BenillaTrainerCostLabel" relativePoint="RIGHT"><Offset><AbsDimension x="5" y="0"/></Offset></Anchor></Anchors>
                <Scripts><OnLoad>SmallMoneyFrame_OnLoad(); MoneyFrame_SetType("STATIC");</OnLoad></Scripts>
            </Frame>

            <!-- ref Blizzard_TrainerUI.xml:338-345, and the reference's own NAME: the purse, a
                 SmallMoneyFrameTemplate with no OnLoad of its own (type PLAYER from the template; repaints
                 on PLAYER_MONEY). Same BOTTOMRIGHT->window BOTTOMLEFT (180,86) seat; the anchor targets OUR
                 window name until this file migrates. Retires BenillaTrainerMoneyCoin1..3 (1937). -->
            <Frame name="ClassTrainerMoneyFrame" inherits="SmallMoneyFrameTemplate">
                <Anchors><Anchor point="BOTTOMRIGHT" relativeTo="BenillaTrainerFrame" relativePoint="BOTTOMLEFT"><Offset><AbsDimension x="180" y="86"/></Offset></Anchor></Anchors>
            </Frame>

            <!-- The Train button (ref ClassTrainerTrainButton): UIPanelButton face + "Train", 80×22, in
                 the detail area's bottom-right. Enabled only for an affordable available service. -->
            <Button name="BenillaTrainerTrainButton" inherits="BenillaTrainerPanelButtonTemplate" text="Train">
                <Anchors><Anchor point="TOPLEFT" relativePoint="TOPLEFT"><Offset><AbsDimension x="184" y="-409"/></Offset></Anchor></Anchors>
                <Scripts><OnClick>BenillaTrainerTrainButton_OnClick()</OnClick></Scripts>
            </Button>
            <!-- The Exit button (ref ClassTrainerCancelButton): hides the window; OnHide fires CloseTrainer(). -->
            <Button name="BenillaTrainerCancelButton" inherits="BenillaTrainerPanelButtonTemplate" text="Exit">
                <Anchors><Anchor point="TOPLEFT" relativePoint="TOPLEFT"><Offset><AbsDimension x="265" y="-409"/></Offset></Anchor></Anchors>
                <Scripts><OnClick>HideUIPanel(getglobal("BenillaTrainerFrame"))</OnClick></Scripts>
            </Button>
        </Frames>
        <!-- The NPC-session lifecycle (MerchantFrame.xml's shape): OnHide calls CloseTrainer() — it ends
             the client-side session whenever this window hides for ANY reason (ESC, close X, Exit,
             TRAINER_CLOSED, or another left-slot window displacing it). The list wheel lives on the
             WINDOW (the engine bubbles a spin up the parent chain, so a spin over a row reaches here). -->
        <Scripts>
            <OnLoad>BenillaTrainerFrame_OnLoad(self)</OnLoad>
            <OnEvent>BenillaTrainerFrame_OnEvent(self)</OnEvent>
            <OnMouseWheel>BenillaTrainerFrame_OnMouseWheel(arg1)</OnMouseWheel>
            <OnShow>BenillaTrainerFrame_ApplyFilter(); PlaySound("igCharacterInfoOpen")</OnShow>
            <OnHide>CloseTrainer(); PlaySound("igCharacterInfoClose")</OnHide>
        </Scripts>
    </Frame>
</Ui>