RenderLayer code

[Antti Koivisto]

Quoting Lars Knoll <lars@trolltech.com>:
> At the same time we have a performance problem with the layer code I have
> to 
> look into. Our painting got slower by a factor of about 5 (just
> estimated). 
> I'll check with the new layer code, but one problem might be that you 
> construct and flatten the ztree on every paint call.

You hadn't integrated the phase checks in paint methods, so everything was
getting drawn (at least) thrice.


  antti