display.c is getting a bit crowded. Move most of the handling
out to another file, events.c.
The long-term goal is to have generic event handling here, with
backend-specific handling for the types of windows and such.
Previously, a sequence like this would crash a client:
=> surface.attach(buffer)
=> buffer.destroy()
The correct behavior is to wait until we release the buffer before
destroying it.
=> surface.attach(buffer)
=> surface.attach(buffer2)
<= buffer.release()
=> buffer.destroy()
The protocol upstream says that "the surface contents are undefined"
in a case like this. Personally, I think that this is broken behavior
and no client should ever do it, so I explicitly killed any client
that tried to do this.
But unfortunately, as we're all well aware, XWayland does this.
Rather than wait for XWayland to be fixed, let's just allow this.
Technically, since we always copy SHM buffers into GL textures, we
could release the buffer as soon as the Cogl texture is made.
Since we do this copy, the semantics we apply are that the texture is
"frozen" in time until another newer buffer is attached. For simple
clients that simply abort on exit and don't wait for the buffer event
anyhow, this has the added bonus that we'll get nice destroy animations.
If we have a CLICKING grab op we still need to send events to xwayland
so that we get them back for gtk+ to process thus we can't steer
wayland input focus away from it.
https://bugzilla.gnome.org/show_bug.cgi?id=726123
meta_wayland_seat_repick() can be called in various cases while mutter
has a GRAB_OP ongoing which means we could be sending wrong pointer
enter/leave events.
https://bugzilla.gnome.org/show_bug.cgi?id=726123
This ensures that we send the proper leave and enter events to wayland
clients.
Particularly, this solves a bug in SSD xwayland windows where clicking
and dragging on the title bar to move the window only works on the odd
turn (unless the pointer moves away from the title bar between
tries). This happens because xwayland gets a button press but doesn't
see the release so when it gets the next button press it discards it
because its pointer button tracking logic says that the button is
already pressed. Sending the proper wayland pointer leave event fixes
it since wayland clients must forget about button state at that point.
https://bugzilla.gnome.org/show_bug.cgi?id=726123
At one point, it was supported to run mutter without a compositor,
but we don't allow that any longer. A lot of code already assumes
display->compositor exists and doesn't check for a NULL pointer,
so just kill the rest of the checks.
