[Baertram]

Thanks for your time and the workaround.
Will implement this function into my inventory updating addons.

If I understand your workaround function right it won't update the inventory if the mouse is currently over any control of an item in the inventory?
I guess this would break addons like FCOItemSaver as you right click an item to show the context menu, choose an entry and afterwards the inventory will be updated. The mouse is above any inventory item after the context menu closes... And thus the inventory update won't happen anymore.

I'll test this if the control is the context menu, as the update fires, or the inventory line again.
And if you mark an item via keybinding it will definately be the inventory item control..