jobjects have to be compared with env->IsSameObject()
and each Activity needs its own Window instance.
The GtkWindow is still shared between all Activities
currently, our "not-actually-a-queue" implementation is quite ugly,
hopefully it might be possible to make it look somewhat sane while
not needing to make it as much of a queue as it is on android
NOTE: the main addition in this commit is WIP support for apps which
render on an EGL surface obtained using ANativeWindow_fromSurface
currently, this EGL surface is obtained by creating a 700x700 pixel
window with GLFW (the 700x700 size is hardcoded in several places)
and only Wayland is supported
ideally, we'd want to use a wayland subsurface to position the EGL
surface above the Surface widget it's associated with (and do
whatever for X11)
