compat.h: compatibility layer for various GTK versions
util_*: generic, non-UI related utilities
ui_*: ui logic related, but gtk-free utilities
wt_*: custom widgets, cell renderers for gtk - must work in both gtk2 and gtk3
dlg_*: dialog boxes, preferably one per file
bu_*: builders, building a part of a bigger gui portion
in_*: input handling (gtk-specific)
glue_*: glue code that should be used by the HID implementations to interface the HID API or by the gtk code to interface the HID implementation

Any of these may depend on glib.
