Sometimes the size will exceed the minimum bounds. For example crazy
applications like the widget factory that contains the world, or when a
user interactively resizes a window to be larger than the monitor the
window is on is.
The former is questionable, but the latter is not, and from here we
can't really see the difference, so just stop complaining.
Closes: https://gitlab.gnome.org/GNOME/gtk/-/issues/3035
GTK will not up front know how to correctly calculate a size, since it
will not be able to reliably predict the constraints that may exist
where it will be mapped.
Thus, to handle this, calculate the size of the toplevel by having GDK
emitting a signal called 'compute-size' that will contain information
needed for computing a toplevel window size.
This signal may be emitted at any time, e.g. during
gdk_toplevel_present(), or spontaneously if constraints change.
This also drops the max size from the toplevel layout, while moving the
min size from the toplevel layout struct to the struct passed via the
signal,
This needs changes to a test case where we make sure we process
GDK_CONFIGURE etc, which means we also needs to show the window and
process all pending events in the test-focus-chain test case.
