A Button release un-pushed the button before `OnMouseUp` and `OnClick` ran, so both read NORMAL. A plain click on a floating chat tab then took the pick-up branch and left the window following the cursor.
In the reference, the mouse-up handler fires `OnMouseUp` first, then reads the state: a PUSHED button with the cursor inside it and the Up registration fires `OnDoubleClick` or `OnClick`, and only then is it set NORMAL, unless locked. A failed gate still un-pushes; an `OnMouseUp` that un-pushes cancels the click.
The release now runs that order after `OnMouseUp`, with the started-drag skip kept.
Tests read the state inside each handler and drive the stock chat tab.
Fixes#699
Co-Authored-By: Claude Sonnet 5.5 <noreply@anthropic.com>
