Someone was asking on the mailing list about doing an application with a Win32 Tray Icon. I said there was no FLTK-specific way to do that, as there is no really portable way to address that particular GUI idiom - but that writing the Win32 platform specific code to support it should be trivial...
Anyway, the resulting code is pretty alpha, and needs some reworking. Seems to do the right thing. It is apparent from the nasty icon I tried to draw that I am no graphics artist, though!
I may work on this some more. Or more likely not... If it works for you, enjoy, if not, too bad.
You will need a copy of FLTK built and installed.
Then you need this zip file, which has the source for this program.
Then type make and hope for the best!
The Makefile uses fltk-config for portability, and assumes you are using the mingw32 compiler toolchain in a Msys shell.
However, there is nothing compiler specific in the code, so this should work with any Win32 compiler toolchain that can build FLTK. You'll have to craft your own Makefile or project though!