This is more important in the client side windows world, as clip masks
may be used for clipping to non-native subwindows. This fixes a bug
in aisleriot where it uses masked pixbuf drawing and it ends up drawing
over the moving card subwindow.
Turns out pygtk build broke due to the argument addition to draw_drawable.
So, we now add a new vfunc for the new draw_drawable and are thus
backwards compat.
we now use gdk_offscreen_window_set_embedder() instead of a signal
to get the parent. This also replaces set_has_offscreen_changes.
Rename "parent" in all embedding related names to "embedder" to make it
more obviously different than the normal parent.
Rename gdk_window_get_offscreen_pixmap to gdk_offscreen_window_get_pixmap
to match the other offscreen calls.
Rename gdk_window_offscreen_children_changed to gdk_window_geometry_changed
as this is more descriptive.
We emulate visibility by unmapping (in X) all mapped (according to
gdk) windows that are not visible (all parents mapped). This is because
there may be client side windows inbetween the native windows in the
hierarchy, so you can't know a native window is visible just because
all the parent native windows are mapped.
However, we don't want to unmap foreign windows, as that may cause all
sort of unexpected issues. This should be safe, because generally the
parent of a foreign window is a native window (e.g. a socket), so its
gdk visibility state is the same as the Xserver one.
This fixes an issue with the GDM notification area where the unmap of
the plug caused spurious UnmapNotify events that confused GtkSocket and
caused icons to become one pixel wide.
Last commit was bad, as it didn't clip against client side
children. This implements such clipping first and then
only clears the rectangles that need to be cleared.
This is how cairo works with native children.
This fixes an issue where the drag target outline is visible on the
evolution folder treeview when it isn't with native windows.
Without this we can't draw to them, which caused problems for e.g.
gnome-settings-daemon clearing the background when the desktop
background changed.
Note: We don't actually clip away child windows from the root window,
the clip is just based on the size of the root window.
