This is just a suggestion. Maybe it's to complicated to program. If it is, no problem. There are already ways in IA to get the results I am after. I just think the way I want to suggest would be easier and more intuitive.
I would like to see the FADE and UNDO and REDO commands work in selections, not just in the image as a whole. I mean selections that are made after a filter is applied. It would go like this.
1. Run a filter on an image.
2. Make a selection (or several selections) in the image, either a rectangular or a mask selection.
3. Fade (or Undo) the effect of the filter in the selected areas only.
This would be the same as the eraser tool in programs with layers. As IA works now, a mask selection uses UNDO to deselect. There would have to be another way to deselect.
If this seems too complicated or unnecessary, I can write a tutorial for the help pages to describe how this can be done with the present version of IA. Maybe others already know, but it has taken me years to figure it out. Actually, it was the last obstacle for me. When I filtered an image of a face and wanted to Fade the effect over the eyes, I would switch to an editor with layers and use the Eraser Tool. Now that I've finally figured out how to do it in IA, I never need the other editor. The method involves several steps. It's not quite as easy as the way I suggested above, but it does work. I am just suggesting this in case it might not be difficult to program and the feature appeals to you, Michael. Either way, IA is the best and fastest and easiest to use photo editor I have ever found.