The main advantage of GTK+ 3 is better support for HiDPI
displays. If GTK+ 3 libraries are not available or if the
`PLT_GTK2` environment variable is defined, GTK+ 2 is used
as before.
Get data from a clipboard client before going into atomic mode. This
correction can avoid an "about to suspend in atomic mode" failure,
particularly if a snip fails to copy correctly.
In particular, restore key handling that makes Ctl-Space produce an
event with a Space character. Also, restore `special-option-key`
support, while correcting the documentation to say what
`special-option-key` and `special-control-key` actually do.
Closes PR 14934
Bindings for UCKeyTranslate.
UCKeyTranslate converts a combination of a key-code, a modifier key state, keyboard layout and dead key state to a unicode string.