Question: How to get control under mouse pointer?

#1 Turns out I was looking in all the wrong places (i.e. in the engine code); needed to look in the tools scripts, guiEditor.ed.cs. The function that I need is findHitControl():

function GuiEditor::onControlDragged( %this, %payload, %position )
{
   // Make sure we have the right kind of D&D.
   
   if( !%payload.parentGroup.isInNamespaceHierarchy( "GuiDragAndDropControlType_GuiControl" ) )
      return;
      
   // use the position under the mouse cursor, not the payload position.
   %position = VectorSub( %position, GuiEditorContent.getGlobalPosition() );
   %x = getWord( %position, 0 );
   %y = getWord( %position, 1 );
   %target = GuiEditor.getContentControl().findHitControl( %x, %y );
   
   // Make sure the target is a valid parent for our payload.
   
   while(    ( !%target.isContainer || !%target.acceptsAsChild( %payload ) )
          && %target != GuiEditor.getContentControl() )
      %target = %target.getParent();
      
   if( %target != %this.getCurrentAddSet() )
      %this.setCurrentAddSet( %target );
}

#2 Incidentally, findHitControl() is a member of GuiControl.

Also, it looks like we have findHitControls() which appears to return all controls within the specified rectangle. Does anyone use this method? Can you tell me more about how you use it?

#3 https://github.com/RichardRanft/Torque2D/tree/inventory - though it would need some work to get it functioning correctly in T3D....

I prefer to use the drag and drop stuff for this sort of thing - and there is direct support in GuiControl for getting info back -

// drag enter and exit callbacks 
IMPLEMENT_CALLBACK( GuiControl, onControlDragEnter, void, ( GuiControl* control, const Point2I& dropPoint ), ( control, dropPoint ),
   "Called when a drag&drop operation through GuiDragAndDropControl has entered the control.  This is only called for "
   "topmost visible controls as the GuiDragAndDropControl moves over them.nn"
   "@param control The payload of the drag operation.n"
   "@param dropPoint The point at which the payload would be dropped if it were released now.  Relative to the canvas." );
IMPLEMENT_CALLBACK( GuiControl, onControlDragExit, void, ( GuiControl* control, const Point2I& dropPoint ), ( control, dropPoint ),
   "Called when a drag&drop operation through GuiDragAndDropControl has exited the control and moved over a different control.  This is only called for "
   "topmost visible controls as the GuiDragAndDropControl moves off of them.nn"
   "@param control The payload of the drag operation.n"
   "@param dropPoint The point at which the payload would be dropped if it were released now.  Relative to the canvas." );

But of course it might depend on what you're doing and how you really need to do it....