Can't smudge mask

[avram]

I'm trying to smudge the edge of a layer mask, and the app won't let me. (Pixelmator Pro v1.3.3 Prism, MacOS High Sierra 10.13.6). Here's the simplified case:

1. I created a new document, default settings.
2. Created a Rectangle Shape layer, bright purple. Now there's a purple rectangle on a white background.
3. Selected the Shape layer, right-clicked, selected "Add Mask." This added an all-white mask thumbnail next to the layer thumbnail.
4. Switched to the Brush tool. Selected a basic brush, black color.
5. Clicked on the mask thumbnail.
6. Painted a diagonal stripe on the mask. Now there’s a white stripe on my purple box. So far, all is as expected.
7. Switched to the Smudge tool. Tried to smudge the edges of that stripe on the mask layer. I got an error sound, and nothing seemed to happen to the mask that I could see.

So what's up with this? The tutorial says "You can use almost any tool in Pixelmator Pro to edit masks, just like you would edit any other type of layer." When I paint a colored stripe directly onto the white background, I can smudge it just fine, but it doesn't work in a mask.

[st3f]

I see the same thing. On both Pixelmator Pro 1.3.3 and 1.3.4 beta the smudge tool smudges the layer, not the mask, regardless of which is selected. I'm hoping that this is a bug and not a consequence of how masks are handled as it would be usful to be able to use the smudge tool on masks.

[Andrius]

The retouching tools don't work on masks and this is by design. We could turn this on as the Smudge tool could probably be pretty useful on layer masks from time to time.