In 2.x, the !HAVE_XCONVERTCASE fallback of keyval_convert_case() was
implicitly used as implementation for all !X11 backends.
In 3.x, when this function was virtualized in GdkDisplayManager,
this fallback was moved to the X11 backend and the other backends
"equipped" with /* FIXME implement */ implementations of
keyval_convert_case() which don't convert anything.
Move the fallback code back to gdk/ as default implementation
of GdkDisplayManager::keyval_convert_case() and remove its
implementations is all backends but X11. Also remove the
implementation in Wayland which was a plain copy of what
is now the default implementation.
(cherry picked from commit f46c1b76d8)
We need to defer setting the default display until the
GdkDisplay is fully initialized. Also, short-circuit some
encoding conversions when creating windows, to avoid an
implicit dependency on the display being in the list of
displays yet.
This commit hides the GdkDisplayManager instance and class structs,
adds vfuncs for listing displays, opening displays, and getting and
setting the default display. The X11 backend has a derived
GdkDisplayManagerX11.
The gdk_display_manager_get() function is responsible for deciding on
which of the compiled in backends to use. Currently, it consults the
GDK_BACKEND environment variable and falls back to x11.
