I think I should summ up the discussion to this point:
1. Most of the user use the magic wand to select and either <control>, or drag and drop or the bucket tool to fill a region. They normaly don't use the threshold.
2. The user interface is not clear. I didn't know that you can drag
and drop to a selection (could someone add this to the "did you know" file?).
A threshold with a selection does not make sense.
That you can fill everything by setting the threshold to 255 is only for advanced users.
3. The bucket fill does not behave like expected. With a active selection the fill should fill a region (as determined by the threshold) but limited to the selection.
4. Too many tools only confuse the user.
5. No one want's to change a UI.
Drag and drop is a good thing. If we could only use it more often. (How about a file icon where you can draw pictures in and out).
We don't want to sacrifice a tool (either the gradient fill or the bucket fill) because other users (from photoshop) know them and would miss them. But how about sacrificing the menu entries "fill with foreground color".
We need to give more clues to the user how to use the features.
How about this threshold fill bar:
The most important point:
We have no one to solve such problems.
If there is a bug, or any other programming issue, everyone could say wrong or right and most of the people will agree.
With the UI there is no such simple solution. We need someone to solve such problems. We need a consistent UI .
Should we elect such a person? Should we let a poll on the web-page solve the UI problems?
If you should elect me (I hope not), my opinion is that a UI should
be fast and small.
Things you do often should be fast to do, things you do seldom should be possible.
Why do we need two or three tools to fill a region? Only because other programs have that much tools?
I say no. One tool should be sufficient.