Hi nick65go
fltk-xft is maintained by polikuo. Lets see what he says.
To enable mouse corners, --enable-xcursor in ./configure and recompile.
libXcursor is already a dependency for xorg, xvesa, xfbdev, flwm. gtk2, gtk3, ...
The cursors that depend on libXcursor are compiled into fltk even with --disable-xcursor.
I saw no increase in extension size with --enable-xcursor.