The color scheme preview in the settings UI no longer works

[j4james]

Windows Terminal version

Commit 094273b

Windows build number

10.0.19041.1348

Other Software

No response

Steps to reproduce

1. Open the Settings UI
2. Navigate to the profile Defaults section.
3. Select the Appearance tab.
4. Flip through different Color scheme options while watching the preview window.

Expected Behavior

The preview should update to reflect the selected color scheme.

Actual Behavior

The preview doesn't change.

I did a git bisect of the code, which reported commit 094273b as the point at which this stop working. However, I'm wondering if perhaps it's an interaction between those changes and the color table refactoring I was doing in #11602 and #11784.

[zadjii-msft]

which reported commit 094273b as the point at which this stop working

That would have been my guess as well. If this is all that broke, that's pretty dang impressive. I'll add this to 1.13 to make sure this gets resolved before shipping. Thanks!

[j4james]

FYI, I think this has got something to do with "unfocused appearance". I could "fix" the issue by changing the line below so it always passes in _core.FocusedAppearance():

terminal/src/cascadia/TerminalControl/TermControl.cpp

Line 252 in 094273b

_UpdateAppearanceFromUIThread(_focused ? _core.FocusedAppearance() : _core.UnfocusedAppearance());

And also changing this call so the parameter hardcoded to true:

terminal/src/cascadia/TerminalControl/TermControl.cpp

Line 313 in 094273b

_core.ApplyAppearance(_focused);

I'm sure that's not the right solution, but that at least gives you an idea of where things are going wrong. It seems to be attempting to use the unfocused appearance when rendering the preview, and in my case that wasn't actually set to anything.

[j4james]

It looks like the problem is that the preview control is created disabled, and with AllowFocusWhenDisabled set to false. Since it can never gain focus, it always renders with the unfocused appearance.

terminal/src/cascadia/TerminalSettingsEditor/Profiles.cpp

Lines 414 to 415 in 094273b

	_previewControl.IsEnabled(false);
	_previewControl.AllowFocusWhenDisabled(false);

One possible fix would be to set the _focused property to true by default when TermControl is created, and rely on the control receiving a lost focus event (when not disabled) to change that to false when necessary. The preview control wouldn't receive those events so would always be viewed as focused.

If there are situations where the _focused property has to be false by default, we could always add the initial focus state as a constructor parameter, or maybe add a method to force the focused state.

I don't know much about the UI side of things, though, so maybe it's more complicated than this. Just throwing out some ideas.

[zadjii-msft]

Yea, that all makes sense. Messing with _focused might just give us a fix for #11411 too. The trick there though is making sure when you're opening a bunch of panes at once that only the last one actually gets the blinking cursor.

But now I'm looking at the pair of these so hopefully I can come up with something

[ghost]

🎉This issue was addressed in #12095, which has now been successfully released as Windows Terminal Preview v1.13.10336.0.:tada:

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