- Added viOpenDefaultDisplay.
- Replaced viOpenLayer with viCreateLayer.
- NativeWindow parcel data is now parsed by viCreateLayer, and the
ViLayer struct contains a new igbp_binder_obj_id field.
- LayerFlags/LayerId parameters replaced by weak global variables
__nx_vi_layer_id/__nx_vi_stray_layer_flags.
- The root vi:* session is closed on startup.
- Simplified corresponding gfx code.
- Misc style fixes