🚀 go-pugleaf

I'm using a Canvas (WorkSpace) where I do my drawing and a PaintBox to
display the results. A Thread is used to draw on WorkSpace and copy the
modified segment into PaintBox. Another procedure, triggered by OnPaint
event, copies the entire WorkSpace into the PaintBox to restore the image.
Semaphore is used to ensure that the restore procedure will not copy an
unfinished image. Canvas are locked while they are in use.

Now, when I move the main form over the form with the PaintBox very fast the
image can't be restored properly. It looks like Windows can detect the
'invalid' area and only updates a small part of the PaintBox, although my
procedure copies the entire image. That's OK. But the 'funny' thing is that
the update segment sometimes appears at the wrong place, somtimes even
somewhere on the screen (outside of the paintbox). Of course, sometimes it
crashes as well :-(

The program was working fine without Thread. Can anyone help?

Thanks
Phuoc


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