Implement min/max size request from xdg-shell-v6 and plug it into the
existing code so that windows with fixed size cannot be tiled/maximized
in Wayland just like in X11.
Bugzilla: https://bugzilla.gnome.org/show_bug.cgi?id=770226
Add support for assigning a window a custom window placement rule used
for calculating the initial window position as well as defining how a
window is constrained.
The custom rule is a declarative rule which defines a set of parameters
which the placing algorithm and constrain algorithm uses for
calculating the position of a window. It is meant to be used to
implement positioning of menus and other popup windows created via
Wayland.
A custom placement rule replaces any other placement or constraint
rule.
https://bugzilla.gnome.org/show_bug.cgi?id=769936
When placing a popup and the legacy transient wl_shell_surface surfaces,
take the current scale of the window into account. This commit doesn't
fix relative positioning in case a window scale would change, but since
the use case for relative positioning is mostly popups, which would be
dismissed before the parent window would be moved, it should not be that
much of a problem.
https://bugzilla.gnome.org/show_bug.cgi?id=744934
