Fix editable ComboBox text contrast in Desert high-contrast theme#790
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amarinov-msft wants to merge 2 commits into
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Fix editable ComboBox text contrast in Desert high-contrast theme#790amarinov-msft wants to merge 2 commits into
amarinov-msft wants to merge 2 commits into
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Use full-contrast WindowText for the editable ComboBox in high contrast (was ~4.292:1) and place the caret at end instead of selecting all on focus, so the value isn't highlighted. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
dipeshmsft
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@amarinov-msft, I think this is more of a WPF's ComboBox style issue. We should be updating the color of TextControlSelectionHighlightColor brush in Fluent.HC.xaml. Similarly, we should try overriding the resource value in the app resources and use that instead. |
…color Fluent's high-contrast theme sets TextControlSelectionHighlightColor to WindowColor, so editable ComboBox text is washed out (unreadable) when auto-selected on focus. Override that resource with the system Highlight color under high contrast, scoped to ComboBoxPage. Keeps standard select-on-focus behavior while making the selected text legible; Light/Dark selection is unaffected. Co-authored-by: Copilot <223556219+Copilot@users.noreply.github.com>
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I updated the approach. Here are the numbers from the Accessibility tool: |
dipeshmsft
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Jul 2, 2026
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| // Fluent's HC selection color is WindowColor, washing out editable text selected on focus; use the Highlight color instead. | ||
| if (SystemParameters.HighContrast) |
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We would need to do something similar to what we did in MainWindow.xaml.cs.
Although, this code would work when the app / page is initialized. However, if we are on the page and the theme changes to something else, it may end up in wrong visuals.
Apart from that this is exactly what I was talking about.
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Summary
Fixes an accessibility issue in the WPF Gallery
ComboBoxpage. The editable ComboBox's focused text rendered at only ~4.292:1 contrast under the Desert contrast theme, below the 4.5:1 minimum required by MAS 4.3.1 and is flagged by Accessibility Insights. The Fluent theme draws the editable text withComboBoxForeground/ComboBoxForegroundFocused, whose Desert color pairing is borderline.Change
Sample Applications/WPFGallery/Views/BasicInput/ComboBoxPage.xaml.csOverride
ComboBoxForegroundandComboBoxForegroundFocusedto full-contrastWindowTextwhenSystemParameters.HighContrastis set, scoped to this page only. On focus, place the caret at the end instead of selecting all text, so the value isn't highlighted.Sample Applications/WPFGallery/Views/BasicInput/ComboBoxPage.xamlHook
GotKeyboardFocuson the editableComboBoxto drive the deselect behavior.Result
Under high contrast the editable
ComboBoxtext renders at the theme's fullWindowTextcolor, above the 4.5:1 minimum, so the Accessibility Insights Text Contrast check passes. Normal Light/Dark appearance is unchanged.Testing
ComboBoxunder the Desert contrast theme (now > 4.5:1, no select-all highlight).Microsoft Reviewers: Open in CodeFlow