Here is a list of all modules:
oCallback function typedefsTypedefs defined in <FL/Fl.H> for callback or handler functions passed as function parameters
oWindows handling functionsWindows and standard dialogs handling declared in <FL/Fl.H>
oEvents handling functionsFl class events handling API declared in <FL/Fl.H>
oSelection & Clipboard functionsFLTK global copy/cut/paste functions declared in <FL/Fl.H>
oScreen functionsFl global screen functions declared in <FL/Fl.H>
oColor & Font functionsFl global color, font functions
oDrawing functionsFLTK global graphics and GUI drawing functions
oMultithreading support functionsFl multithreading support functions declared in <FL/Fl.H>
oSafe widget deletion support functionsThese functions, declared in <FL/Fl.H>, support deletion of widgets inside callbacks
oCairo Support Functions and Classes
oUnicode and UTF-8 functionsFl global Unicode and UTF-8 handling functions declared in <FL/fl_utf8.h>
oMac OS X-specific symbolsMac OS X-specific symbols declared in <FL/x.H> or <FL/gl.h>
oCommon Dialogs classes and functions
\File names and URI utility functionsFile names and URI functions defined in <FL/filename.H>