High Contrast
Windows High Contrast is an accessibility setting, not a visual preference. Users who enable it have committed to a specific high-contrast color scheme for everything on screen, and Microsoft's accessibility guidelines require applications to let the user's scheme win over any application-chosen colors. SftTabs/DLL 7.0 follows this rule automatically.
When Windows High Contrast is active, the tab control:
- renders backgrounds in COLOR_WINDOW, text in COLOR_WINDOWTEXT, active-tab highlight in COLOR_HIGHLIGHT / COLOR_HIGHLIGHTTEXT, and similar for other roles,
- ignores caller-supplied color overrides (SetCtlColors, per-tab colors in SFTTABS_TAB) on the default render path - the user's contrast theme wins,
- suppresses Windows themes so the control falls back to the non-themed GDI path that honors system colors directly.
The tab control's high contrast setting has three values (see SetHighContrastMode):
| AUTO (default) | Follow the Windows High Contrast setting. The control re-renders when the setting flips. |
| ON | Always use the system palette, regardless of the Windows High Contrast setting. Useful for testing or for applications that want consistent high-contrast rendering for a specific tab control. |
| OFF | Ignore the Windows High Contrast setting and render normally. Not recommended in shipping applications - it means users with accessibility needs will see rendering that does not comply with their contrast theme. |
SFTTABSN_HIGHCONTRAST_CHANGED is sent to the parent window each time the active state flips (AUTO mode only) so the application can repaint its own chrome to match. IsHighContrastActive reports the current state at any time.
Owner-drawn tabs (SFTTABS_DRAWTABPROC) are responsible for their own high-contrast compliance. Owner-draw code should query IsHighContrastActive and re-map its role colors to system-palette values when the return value is TRUE. Failing to do this makes owner-drawn tabs unreadable under a user's high-contrast theme.
Dark mode and Windows High Contrast are independent. If the user has both enabled, high contrast takes precedence - the contrast theme's palette wins over the dark palette, because honoring the user's contrast theme is the stronger accessibility requirement.
On
Off