Paintop preview usuability

[Lukast dev]

Hi

> * but more important to me, currently the preview works only for paint
> paintop (the one that add colors) while for modifying paintop (eraser,
> filter, smudge, deform, duplicat) the area remains white. What we would need
> for those paintop is to draw on a non-transparent layer, with some kind of
> pattern (a checker ?) and to render the layer on a background with a
> different color so that transparency is visible.

Good idea with non-transparent checker layer +1

> What I am wondering is wether we want to have different settings of the
> preview (transparent layer + white background for paint pantop, and pattern
> for modifying paintop), or we use the same for all paintops ?

I think it is clever to do two different settings as you suggested.