GtkScalingFilter not applied to GL texture from a shared context
Presumably this is because gsk_gl_driver_load_texture
returns the texture ID as-is when it comes from a shared context, despite the texture potentially having different scaling filters set than the ones that GTK wants to draw it with.
A concrete use-case this breaks is when showing OpenGL textures coming from GStreamer: they have GL_LINEAR
scaling set, so there's no way to draw them using nearest scaling. However, this can break the other way around too: if some texture has a different scaling set, but GTK wants to draw it with linear scaling.
Allegedly the way to fix this is with texture views, although they aren't supported on all GL versions that GTK cares about.