shell: Preserve fullscreen state when moving window between workspaces

src/shell/mod.rs

@@ -3128,7 +3128,18 @@ impl Shell {
         let from_workspace = self.workspaces.space_for_handle_mut(from).unwrap(); // checked above
 
         let is_minimized = window.is_minimized();
-        let mut window_state = from_workspace.unmap_surface(window)?.1;
+        let is_fullscreen = from_workspace.get_fullscreen().is_some_and(|f| f == window);
+        let mut window_state = if is_fullscreen {
+            let (previous_state, previous_geometry) = from_workspace.take_fullscreen().unwrap();
+            WorkspaceRestoreData::Fullscreen(previous_state.zip(previous_geometry).map(
+                |(previous_state, previous_geometry)| FullscreenRestoreData {
+                    previous_state,
+                    previous_geometry,
+                },
+            ))
+        } else {
+            from_workspace.unmap_surface(window)?.1
+        };
 
         toplevel_leave_workspace(window, from);
         if from_output != to_output {

src/shell/workspace.rs

@@ -1235,6 +1235,26 @@ impl Workspace {
         res
     }
 
+    #[must_use]
+    pub fn take_fullscreen(
+        &mut self,
+    ) -> Option<(
+        Option<FullscreenRestoreState>,
+        Option<Rectangle<i32, Local>>,
+    )> {
+        let surface = self.fullscreen.take()?;
+        if surface.ended_at.is_some() {
+            self.fullscreen = Some(surface);
+            return None;
+        }
+
+        for focus_stack in self.focus_stack.0.values_mut() {
+            focus_stack.retain(|t| t != &surface.surface);
+        }
+
+        Some((surface.previous_state, surface.previous_geometry))
+    }
+
     #[must_use]
     pub fn remove_fullscreen(
         &mut self,