We are going to have a new unified interface to build window after tauri-apps/wry#163. It should cover most usage in Tauri.
But there are still many missing features for gtk. Below is the list of features (but not limited to):

• window methods (see comment below)
• events (see comment below)
• platform traits (need to discuss what traits and methods are needed)
• monitor module
  • MonitorHandle
  • VideoMode