Some enhancements for the UI dealing with Global Selection Mask:
(1) Always show Global Selection Mask
Currently, Krita can show the global selection mask in the Layers Docker, when a selection is activated. However, I think it would be better if the mask can be shown even when no selection is activated, for the following reasons:
- Users may want to create a selection by painting on the mask;
- Always showing the mask improves the consistency in Layers Docker (no layer showing/hiding when selecting/de-selecting).
(2) Allow "Activate previous layer" action to select Global Selection Mask, when it appears in Layer Docker
Currently "Activate previous layer" action cannot select Global Selection Mask, but it can select normal transparency masks. I think this should be made consistent, as they are all nodes appearing in the Layer Docker.
(3) Different colours for masks and paint layers.
When users switch from paint layers (painting) to selection/transparency masks, chances are they want a different colour (pure black) to get a 100% opaque selection. It would be better if masks and layers can have different colour stacks.