We want to keep the wl_surface around, because surfaces create their
resources on construct and keep them until destroyed. See the HWND ond
Windows and the XWindow on X11.
This is relevant for graphics resources, where we want to have access
to the VkSurface and eglSurface while the GdkSurface is hidden.
We also want these surfaces to be permanent and not change during the
lifetime of the GdkSurface.
What we can - and must - destroy however are the xdg surfaces, because
those handle visibility on screen.
And we also need to ensure no buffer is attached, so that during the
next creation of the xdg surface we don't get a protocol error.
Instead of setting the buffer scale via the buffer-scale command, set it
via the viewport.
This technically allows setting fractional scales, but we're not doing
that.
April fools!
No, really.
The fractional scale protocol is just a way to track the surface scale,
but not a way to draw fractional content.
This commit uses it for that, so tht we don't rely on tracking outputs.
This also allows magnifiers etc to send us a larger (integer) scale if
they would like that, that is not represented by the outputs.
Add a new flag to track whether buffer scale is dirty or not,
and centralize calling wl_surface_set_buffer_scale() in a single
place: gdk_wayland_surface_sync_buffer_scale().
gdk_wayland_surface_sync_buffer_scale() is only called by
gdk_wayland_surface_sync(), which itself is called by the GL,
Vulkan, and Cairo contexts, right before submitting a frame.
This ensure that each frame has an up-to-date buffer scale.
This mimics how opaque and input regions are tracked.
