If the user did *not* configured a specific monitor, we prefer the
primary monitor. However, if that monitor is disconnected, yambar
would exit with:
no matching monitor
This patch changes this, to use the *last* connected monitor. It also
improves the error message.
Note: if the user did specify a monitor in the configuration, but
perhaps misspelled it, we will *not* fallback to another monitor, but
instead log an error saying that specific monitor could not be found.
This allows the backend to support multi-seat "properly", by checking
against the correct seat. Before this, when we used a single, global
xcursor value, a seat whose pointer needed to be updated would not be
updated.
This is trivial in the Wayland backend; just instantiate a pixman
pointing to the same mmapped memory as the wayland buffer.
In the XCB backend, we change the implementation slightly; instead of
rendering via a cairo XCB surface backend (to a server side pixmap),
which is then blitted to the window in commit(), we now render to a
client-side pixman pixmap, and blit it using xcb_put_image() in
commit().
All decoration, particle and module interfaces now takes a
pixman_image_t parameter, and all drawing is done using pixman APIs.
The wayland/xcb backends implement a new interface functions,
get_pixman_image(), that should return a pixman image instance that is
suitable for rendering.
In the wayland backend, the image uses the same backing data as the
cairo surface.
In the XCB backend, we create a new image each time, and then blit it
to the cairo surface at commit time.
