When a popup is already showing, and gdk_surface_present_popup() is
called, if the layout didn't change, we're not really interested in
relayouting.
In the future, we'll be able to get notified if position of the popup
would change by some environmental changes, but until then, just don't
support it.
Replace the gdk_surface_move_to_rect() API with a new GdkSurface
method called gdk_surface_present_popup() taking a new GdkPopupLayout
object describing how they should be laid out on screen.
The layout properties provided are the same as the ones used with
gdk_surface_move_to_rect(), except they are now set up using
GdkPopupLayout.
Calling gdk_surface_present_popup() will either show the popup at the
position described using the popup layout object and a new unconstrained
size, or reposition it accordingly.
In some situations, such as when a popup is set to autohide, presenting
may immediately fail, in case the grab was not granted by the display
server.
After a successful present, the result of the layout can be queried
using the following methods:
* gdk_surface_get_position() - to get the position relative to its
parent
* gdk_surface_get_width() - to get the current width
* gdk_surface_get_height() - to get the current height
* gdk_surface_get_rect_anchor() - to get the anchor point on the anchor
rectangle the popup was effectively positioned against given
constraints defined by the environment and the layout rules provided
via GdkPopupLayout.
* gdk_surface_get_surface_anchor() - the same as the one above but for
the surface anchor.
A new signal replaces the old "moved-to-rect" one -
"popup-layout-changed". However, it is only intended to be emitted when
the layout changes implicitly by the windowing system, for example if
the monitor resolution changed, or the parent window moved.
