Translates the contents of a `GdkEventKey` into a keyval, effective group, and level.
Modifiers that affected the translation and are thus unavailable for application use are returned in
effective_group is the group that was actually used for the translation; some keys such as Enter are not affected by the
active keyboard group. The
level is derived from
consumed_modifiers gives modifiers that should be masked out from
state when comparing this key press to a keyboard
shortcut. For instance, on a US keyboard, the `plus` symbol is shifted, so when comparing a key press to a `<Control>plus` accelerator `
<Shift>` should be masked out.
This function should rarely be needed, since `GdkEventKey` already contains the translated keyval. It is exported for the benefit of virtualized test environments.
a modifier state
active keyboard group
return location for keyval
return location for effective group
return location for level
return location for modifiers that were used to determine the group or level
true if there was a keyval bound to keycode/state/group.