With only get_preferred_width and get_preferred_height implemented,
we end up calling the GtkBin height_for_width implmementation, which
knows nothing about the margins and paddings that GtkPopover needs.
As a result, a listbox added to a popover was getting cut off
at the bottom.
This property is TRUE by default, when a popover is modal, it
will automatically set a GTK+ grab on the popover, and grab
the keyboard focus into the popover.
Popovers are strange in the sense that they aren't attached to a
parent directly, they rely on the relative_to widget so the toplevel
is shared, and when they have a parent, it is the toplevel itself,
not relative_to. This also means that there are conditions where the
popover loses it's parent, so they must survive unparenting.
The previous code would be floating the last reference as soon as the
parent is gone, but it was non-obvious who'd own that reference. So
fix this situation by granting the ownership of popovers to their
relative_to widget, an extra reference may be held by the toplevel
when the popover has a parent, but the popover object will be
guaranteed to be alive as long as the parent lives.
This way, memory management of popovers is as hidden from the user
as regular widgets within containers are, users are free to call
gtk_widget_destroy() on a popover, but it'd eventually become
destructed when relative_to is.
When a popover is focused, the focus is forwarded so the first
child what would get the focus actually gets it. Also, implement
correct focus chain, so the keyboard focus stays within the popover
when navigating with keyboard.
This makes it possible to move/resize client-side decorated windows that are
otherwise obscured by a GTK+ grab somewhere else, either a popover within the
window itself or a modal dialog above the window.
This offers the same behavior, but GDK_WINDOW_TEMP windows aren't used
anymore, involving less translations from/to root coordinates, plus no
glitches in having handles snap to content as windows move.
If there is a GTK+ grab on the popover, ensure that it's removed when it's
unmapped. If no GTK+ grab was performed on the popover, this function will
do nothing.
Those functions aren't as useful anymore, hiding/showing can be
controlled by setting the widget visibility, and grabbing can be
achieved by performing a GTK+ grab.
GdkWindows are gone now from the API, the pointed_to rectangle
is from now on relative to the widget allocation. GtkTextView
and GtkEntry were updated to adapt to this change.
This is not as necessary now that bubble windows are popovers, if
a modal behavior is wanted on popover contents, a GTK+ grab on the
popover widget will suffice.
Popovers are transient floating widgets that are confined to the
window space. These have their own GdkWindow that is set on top
of the regular window contents, so they can be used for popup menu
alike UIs with custom popup/popdown/grabs behavior.
