This is a partial revert of e359094cff
window->wl.{width, height} and window->wl.current.{width, height}
represent different things. The former represents the actual size of the
egl surface viewport used for terminal rendering. The former represents
the size of the entire window including the CSD (client side decorations).
These numbers should be the same if CSD is disabled.
The current version of GNOME has a regression that causes the compositor
to send incorrect geometry with the next configure event if the CSD
buffers are created after a call to set_window_geometry.
So call set_window_geometry last. And shake head sadly.
We make use of the fact that wayland tells us when the window is being
resized to track actual user requested sizes as opposed to compositor
requested ones.
The co-ordinates are in the surface co-ordinate system. When the
compositor specifies sizes it apparently adds one subsurface size
in both x and y directions, not both. Possibly because the origin is
placed after the top and left subsurfaces. So modify it by adding
and extra subsurface size to that.
The numbers dont make logical sense, but they do what is expected on
GNOME and since only GNOME is stupid enough to insist on CSD, that's
all we care about.
