Doxygen will now document *Callbacks enums.
Merge branch 'master' of github.com:gupascal/TGUI
Add some doxygen comments on Callback enums.
Allow widgets to be placed in any square of Grid
Merge branch 'master' of https://github.com/gupascal/TGUI into gupascal-master
Slightly changed the docs of callback triggers
Fixed unused parameter warning