🚀 go-pugleaf

Rather than using invalidate rect, you need to erase the image of the icon
at the old position and then redraw it at the new position.  In addition,
if the bounding rectangles for the old and new positions overlap, you
need to do this in a buffer first, then BitBlt the buffer to the screen
just once.  Petzold elaborates upon this subject in his Checkers article
in March 1990 Microsoft Systems Journal, under the subheading, "Moving
the pieces without flicker".

Hope this helps.