Qt editor alpha

[anntzer]

Make alpha values accessible through the Qt figure options editor. Requires #6382 (alpha support in matplotlib.colors), closes #6196.

[tacaswell]

@anntzer this needs a rebase after your other PR got merged.

[anntzer]

Nope, it's still fine.

[tacaswell]

github/The web UI disagrees with you about this needing a rebase.

[anntzer]

Sorry, I was confused by your message on the other PR regarding it being pulled in (which is not the case). Anyways, rebased both PRs.

[anntzer]

By the way, I would appreciate if someone did some manual testing of this PR too, because the figure options UI is not unit-tested (and that would not be so easy to do...).

[tacaswell]

👍 does what it says on the tin.

Looks like this needs a rebase.

[anntzer]

Apparently I also needed to call line.set_alpha explicitly for the alpha value to be set, not sure if something changed recently (I think this wasn't the case before).

[tacaswell]

If I change those lines back to line.set_color(color) it works as expected for me.

[anntzer]

What did you try? If I call plot([1, 2], alpha=.5) then try to edit the alpha of the line, the alpha is actually not modified (when it's just line.set_color(color)).

[tacaswell]

Ah, I was starting with a full alpha line and then turning it down.

[QuLogic]

Ping? Milestone changed to match with #6382.

[anntzer]

Should be good to go? The issue with the need to explicitly call line.set_alpha is an independent one.

[QuLogic]

Hmm, this doesn't backport cleanly. Do you mind opening another PR for it?

[anntzer]

Should I cherry-pick this to upstream/v2.x?

[QuLogic]

Yes, it just doesn't do so cleanly. I'm sure you'll be able to figure it out though.

[anntzer]

I gave it a try; I think that short of rewriting the PR from scratch it's going to be tough to de-interleave it from my other editor-related PRs that went into master but not v2.x (#5469, #6346, #6347, #6366).

[tacaswell]

@anntzer Go ahead and backport all of the editor code if that is easier.