https://bugs.winehq.org/show_bug.cgi?id=45899
--- Comment #24 from Konrad Materka kmaterka@wp.pl --- Forget about window mask change - I found how to do it, it won't work. I will use xcb_shape_get_rectangles to get clickable area.
I guess there is nothing to be done on wine side. I will continue in KDE bug tracker: https://bugs.kde.org/show_bug.cgi?id=399234