Close workspaces view if window spawns while open

We may want to adjust this if it sometimes leads to confusing behavior.
This may be better for now anyway.

Fixes https://github.com/pop-os/cosmic-workspaces-epoch/issues/28.

src/main.rs

@@ -435,6 +435,10 @@ impl Application for App {
                             info,
                             img: None,
                         });
+                        // Close workspaces view if a window spawns while open
+                        if self.visible {
+                            return self.hide();
+                        }
                     }
                     backend::Event::UpdateToplevel(handle, info) => {
                         if let Some(toplevel) =