Too little contrast in progress indicator of inactive tab in light theme

[KalleOlaviNiemitalo]

Windows Terminal version

1.20.11381.0

Windows build number

10.0.19045.4529

Other Software

No response

Steps to reproduce

Configure the terminal to use the light theme (not legacy), and a tab bar separate from the title bar.
Open a PowerShell tab and run a command to output the OSC that sets 50% progress: "`e]9;4;1;50`e\"
Do the same in another tab.

Expected Behavior

The progress indicators in the tab bar should have good contrast so that I can see how much progress has been made.

Actual Behavior

The progress indicator of the inactive tab is too light and doesn't have enough contrast to the light background:

Compare to the dark theme, where both progress indicators have adequate contrast:

[KalleOlaviNiemitalo]

Huh, it seems the color of the progress indicator is coming from the highlight color in the Windows personalization settings…

That seems unreasonable to me; Terminal can't expect that color to have good contrast against both light and dark backgrounds.

[KalleOlaviNiemitalo]

AFAICT, the Terminal doesn't configure the color of the progress ring:

terminal/src/cascadia/TerminalApp/TabHeaderControl.xaml

Lines 18 to 27 in 27fff2c

	<mux:ProgressRing x:Name="HeaderProgressRing"
	Width="15"
	Height="15"
	MinWidth="0"
	MinHeight="0"
	Margin="3,0,8,0"
	IsActive="{x:Bind TabStatus.IsProgressRingActive, Mode=OneWay}"
	IsIndeterminate="{x:Bind TabStatus.IsProgressRingIndeterminate, Mode=OneWay}"
	Visibility="{x:Bind TabStatus.IsProgressRingActive, Mode=OneWay}"
	Value="{x:Bind TabStatus.ProgressValue, Mode=OneWay}" />

So… should I blame Microsoft.UI.Xaml, or is the Terminal violating some MUX guideline about background colors behind the progress ring control?

[zadjii-msft]

I have this gut feeling that this was fixed in Windows 11:

I bet the accent color logic got updated to be smarter in Win11

[zadjii-msft]

Yea, it looks like there was a lot of work in this area in Windows 11. Clearly these aren't all publicly accessible issue threads, but there is a lot of discussion in the win11 timeframe about accent colors:

• MSFT:25681566
• MSFT:30833850
• MSFT:26006362
• ContentDialog Text Color Contrast microsoft-ui-xaml#2354

I'm guessing that a backport to Win10 is highly unlikely. I have no idea how challenging this would be to workaround - possibly prohibitively hard. I don't think WinUI 2 lets us easily restyle the progress ring.