If I draw a canvas over a transparent canvas and make this canvas invisible again then you still see a transparent box where this canvas was drawn. I have to resize the window to let this disappear. Is there another way to achieve this?
Thank you for a solution.
Do you invalidate the lower Canvas after you’ve made the above one invisible? That should remove the Box if it is not done automagically.
BTW: Wouldn’t it make more sense do draw into the already available Canvas instead of draweing another one above it? 
Hi Sascha,
Invalidate is not working., I tried that.
I use a lot of canvasses for instance to create buttons ect in my own style.
Thanks for your attention.
Would calling Invalidate on the window solve the problem?
No, that doesn’t do anything.
Thank you.