[Lazarus] Unneeded Paint calls from LCL

[Marc Weustink]

AlexeyT via lazarus wrote:
> Details:
> Linux gtk2: LCL calls Paint 5 times for ATSynEdit on FormCreate/FormShow:
> 
> 1- DoOnResize - i filtered it out
> 2- DoOnResize - i filtered it out
> 3- Paint - it's ok
> 4- Paint again - i cannot filter it out
> 5- Paint again
> 
> Win32: LCL calls Paint 3 times:
> 
> 1- Paint - it's ok
> 2- DoOnResize - i cannot filter it out
> 3- DoOnResize again
> 
> Can you optimize it to call Paint once, and DoOnResize BEFORE Paint?

IMO paint should be never called directly. When resizing, invalidate 
should be called (so one pain message is issued after the resize)

Marc