Refresh the FPS & Lag panel tooltip while it is shown

The tooltip was built once on enter, so its memory, network and addon
figures stayed at the values from that moment. The widget's one-second
ticker now rebuilds it while the panel still owns GameTooltip. The
tooltip takes its owner as self, not this, so the ticker can call it.

modules/panel.lua

@@ -105,11 +105,12 @@ pfUI:RegisterModule("panel", function()
 
     do -- FPS & Lag
       local widget = CreateFrame("Frame", "pfPanelWidgetLag", UIParent)
-      local lag, fps, laghex, fpshex, _
-      widget.Tooltip = function()
+      local lag, fps, laghex, fpshex, owner, _
+      widget.Tooltip = function(self)
+        owner = self
         local active = 0
         GameTooltip:ClearLines()
-        GameTooltip_SetDefaultAnchor(GameTooltip, this)
+        GameTooltip_SetDefaultAnchor(GameTooltip, self)
         GameTooltip:AddLine("|cff555555" .. T["Systeminfo"])
         for i=1, GetNumAddOns() do
           if IsAddOnLoaded(i) then
@@ -202,6 +203,10 @@ pfUI:RegisterModule("panel", function()
         end
 
         pfUI.panel:OutputPanel("fps", fps .. " " .. T["fps"] .. " & " .. lag .. " " .. T["ms"], widget.Tooltip, widget.Click)
+
+        if owner and GameTooltip:IsOwned(owner) then
+          widget.Tooltip(owner)
+        end
       end)
     end