pub fn move_to_top(&mut self, handle: &WindowHandle<H>) -> Option<()> {
        let index = self.windows.iter().position(|w| &w.handle == handle)?;
        let window = self.windows.remove(index);
        self.windows.insert(0, window);
        self.sort_windows();
        Some(())
    }
Moves `handle` in front of all other windows of the same order of importance.
See `sort_windows()` for the order of importance.
leftwm-core/src/state.rs