If a surface is not on any output, scheduling a repaint for it is a no-op.
weston_view_schedule_repaint() schedules repaints for all outputs that
overlap with the surface extents, but if the surface is completely
outside all outputs nothing will be scheduled. Fix this for now by starting
the slide slightly into the output.
The input-panel codes tries to see determine if a buffer has not yet
been attached (or a NULL buffer has been attached), and doesn't map
the input panel surface yet in that case. However, it test for
buffer_ref being NULL, which can happen for other reasons. The right
test is to see if surface->width is 0, which means that either a
buffer hasn't yet been attached or a NULL buffer has been attached.
https://bugs.freedesktop.org/show_bug.cgi?id=72519
If we're not currently showing the input panels, we still need to set the
panel position so that it's set when we later need to show them. This fixes
the initial flicker of the input panel in the wrong position when we first
show it.
