Fix issue 14198: [Dark Mode] Improve visual contrast of the Group Headers in ListView control in dark

[SimonZhao888]

Fixes #14198

Proposed changes

Customer Impact

Regression?

• Yes / No

Risk

Screenshots

Before

After

Test methodology

Accessibility testing

Test environment(s)

[Copilot]

Pull request overview

This PR targets WinForms ListView dark mode rendering by improving the visual contrast of group headers (and related group text) when groups are enabled.

Changes:

• Adds custom dark-mode rendering logic for group header text, chevron, subtitle, and footer.
• Adjusts custom-draw flags and text color handling to receive group-related draw notifications and control group text colors.
• Updates the applied dark-mode theme identifier for the ListView/ColumnHeader to use the ItemsView theme.

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[Copilot]

Pull request overview

Improves ListView group header readability in dark mode by adjusting theming/custom-draw behavior and adding an overlay render pass to redraw group header/subtitle/footer with higher-contrast styling.

Changes:

• Add dark-mode overlay drawing for group header/subtitle/footer and a custom chevron/underline rendering path.
• Adjust ListView custom draw flags/colors so group custom-draw notifications are raised and native group text is suppressed in dark mode.
• Switch the applied dark-mode theme identifier to DarkMode_ItemsView and attempt to configure group text colors via LVM_SETGROUPMETRICS.

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[LeafShi1]

Please consider Copilot's suggestion and complete the PR description

[SimonZhao888]

Please consider Copilot's suggestion and complete the PR description

I'm trying to add a selected overlay to a Group Item in Dark Mode.