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Dark mode UI — system-aware Windows 10 dark theme integration

Workflow status is tracked in GitHub: https://github.com/emulebb/emulebb/issues/12. This local document is retained as an engineering spec/evidence record.

Summary

Windows 10 (1809+) supports a system-wide dark mode toggle. Applications that do not opt in display with a white/light window chrome even when the user has selected dark mode, which is jarring on a dark desktop. eMule currently does not implement any dark mode support.

eMuleAI implements a comprehensive CDarkMode class that: 1. Detects the Windows dark mode preference via the registry 2. Hooks into the application's window creation to apply dark theming 3. Provides a full color mapping for all eMule UI elements (custom-drawn list views, progress bars, tab borders, server status colors, IRC colors, menu sidebar, etc.) 4. Integrates with DwmApi (Dwmapi.lib) for dark title bar support

eMuleAI Reference Implementation

Source files: - eMuleAI/DarkMode.cpp — full implementation - eMuleAI/DarkMode.h — class interface and 30+ color constant definitions

GitHub references from eMuleAI commit 8e34bdec2b7e4fe9e4307df9d80f691804be99ed:

Color system: eMuleAI defines a parallel color ID space (COLOR_SHADEBASE=1000 through COLOR_IRC_ACTION_MSG=1025) that overlays the standard MFC color IDs, allowing existing custom-draw code to query themed colors by constant.

Custom color IDs:

#define COLOR_SHADEBASE             1000
#define COLOR_SEARCH_DOWNLOADING    1001
#define COLOR_SEARCH_STOPPED        1002
#define COLOR_SEARCH_SHARING        1003
#define COLOR_SEARCH_KNOWN          1004
#define COLOR_SEARCH_CANCELED       1005
#define COLOR_MAN_BLACKLIST         1006
#define COLOR_AUTO_BLACKLIST        1007
#define COLOR_SPAM                  1008
#define COLOR_SERVER_CONNECTED      1009
#define COLOR_SERVER_FAILED         1010
#define COLOR_SERVER_DEAD           1011
#define COLOR_PROGRESSBAR           1012
#define COLOR_SELECTEDTABTOPLINE    1013
#define COLOR_TABBORDER             1014
// + MenuXP sidebar/title gradients, tooltip theme colors

Tooltip theming: TooltipThemeColors struct defines separate dark/light color sets for tooltip backgrounds and caption backgrounds.

Dependencies

  • Dwmapi.lib — #pragma comment(lib, "Dwmapi.lib") (always present on Win10)
  • DWM_WINDOW_CORNER_PREFERENCE, DwmSetWindowAttribute — for rounded corners and dark title bar (Win10 1809+ / Win11)
  • FEAT-017 (DPI awareness) — dark mode and Per-Monitor V2 DPI should land together; a blurry app in dark mode is doubly bad

Implementation Notes

Dark mode detection in Windows uses the registry:

HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Themes\Personalize
AppsUseLightTheme (DWORD) = 0 → dark mode active

Win11 also supports DwmSetWindowAttribute(DWMWA_USE_IMMERSIVE_DARK_MODE) to request a dark title bar from the compositor.

The main challenge is eMule's extensive custom-drawn list controls (CMuleListCtrl, CListCtrlX, download/shared lists). Each must be updated to query the themed color instead of a hardcoded GetSysColor() value.

Priority Note

This is a Minor UX feature, but it has high visibility — every Windows 10/11 user with dark mode enabled immediately notices the mismatch. It pairs naturally with FEAT-017 (DPI awareness) as both are "modern Windows UI" improvements.

Acceptance Criteria

  • [ ] System dark mode preference detected at startup and on WM_SETTINGCHANGE
  • [ ] Title bar rendered in dark mode (via DwmSetWindowAttribute)
  • [ ] Main window background, list views, tab controls use dark colors when active
  • [ ] Status bar, toolbar, progress bars themed
  • [ ] Preferences panel indicates current theme
  • [ ] No regression in light mode rendering
  • [ ] Preferences toggle: force light/dark/auto (follow system)
  • [ ] screenshot evidence covers main views, preferences, menus, tooltips, progress bars, and high-volume lists in light and dark mode