On Thursday, 5 March 2015 at 13:38:58 UTC, Vadim Lopatin wrote:
Probably DlangUI fits your requirements.
https://github.com/buggins/dlangui
It's written in D, so can be easy extended.
Cross platform - backend part is separated, and new platforms
support can be added. So far, win32 and SDL2 backends are
implemented. There is as well X (XCB) backend, but now it's
abandoned.
Look and feel can be customized using themes and styles.
Unfortunately, if it doesn't cover all major PC platforms, it
doesn't suit me (Mac OS is not supported). I would like to have
all backends working on all platforms, as I lack knowledge to
implement my own backends for X and Mac OS.