The basic MetaShadowFactory type is moved to a public header, while
the functions to fetch and paint shadows are kept private.
The public object will be used for configuration of shadows by
plugins.
https://bugzilla.gnome.org/show_bug.cgi?id=592382
For attached modal dialogs, we want the shadow to fade out at the top
as if the window was glued to the parent at the top. Add a
shadow-top-fade property to MetaWindowActor and the corresponding
parameter to meta_shadow_factory_get_shadow().
The internal implementation of MetaShadow is adjusted to work
in terms of an "inner border" and "outer border" instead of doing
the calculations in terms of an aggregate border and the spread
of the shadow. The old way of doing things gets clumsy when the
top_fade distance is added in as well.
https://bugzilla.gnome.org/show_bug.cgi?id=592382
The current shadow code just uses a single fixed texture (the Gaussian
blur of a rectangle with a fixed blur radius) for drawing all window
shadows. This patch adds the ability
* Implement efficient blurring of arbitrary regions by approximating
a Gaussian blur with multiple box blurs.
* Detect when multiple windows can use the same shadow texture by
converting their shape into a size-invariant MetaWindowShape.
* Add properties shadow-radius, shadow-x-offset, shadow-y-offset,
shadow-opacity to allow the shadow for a window to be configured.
* Add meta_window_actor_paint() and draw the shadow directly
from there rather than using a child actor.
* Remove TidyTextureFrame, which is no longer used
https://bugzilla.gnome.org/show_bug.cgi?id=592382
