Repaint Questions

Edited: based on answer from @hmr i include his suggestions and provide the complete code if i have a component such as

I have an application that can create a rectangle that decreases in size for example a lapse of time of 10 sec, but here is when i try to shrink

I'm experiencing an odd behaviuor in safari. on a quite content-rich page, upon specific user action (that requires relayouts and