Nowadays ReactOS includes support for htmlhelp.h and a working implementation of HHCTRL.OCX. Although current imported HHCTRL.OCX suffers of this issue:
https://bugs.winehq.org/show_bug.cgi?id=47379
See also CORE-15019
+ Revert 'intptr_t' to 'size_t'.
- Fix errors if a theme api is missing.
- Add callback to functions for drawing themed transparent background.
- Fix drawing glitch when theming is applied.
- Redraw on theme change: automatically redraw the window if the
theme is changed while the application is active.
- Colours are now declared though RGB() macro.
- Removed safe DS_SHELLFONT declaration.