fix(gui): name the window so Linux taskbars pair it with its entry

- The window never had a title, so taskbars and window lists showed it as untitled on every Linux desktop; it is now titled "Midi Harbor". The header draws its own title, which is why it went unnoticed.
- On X11 the window's class comes from argv[0], because the pinned libcosmic replaces its X11 window attributes with its Wayland ones. The desktop entry's StartupWMClass is now midi-harbor, the class a package install gets, so X11 taskbars match the window to its entry and icon; Wayland still pairs by the application ID.

crates/gui/src/app.rs

@@ -784,7 +784,7 @@ impl cosmic::Application for App {
         activity_filter.insert().text("Problems only");
         activity_filter.activate_position(0);
 
-        let app = App {
+        let mut app = App {
             core,
             nav,
             page: Page::Endpoints,
@@ -810,6 +810,12 @@ impl cosmic::Application for App {
         // have filled.
         let connect =
             cosmic::task::future(async { Message::Connected(Client::connect(socket).await) });
+        // The window's title, which taskbars and window lists show; libcosmic leaves it empty,
+        // and the header draws its own.
+        let connect = match app.core.main_window_id() {
+            Some(id) => Task::batch([connect, app.set_window_title("Midi Harbor".to_owned(), id)]),
+            None => connect,
+        };
         // The menus as a message rather than now: the window is set up before the event loop
         // runs, and winit builds its default menu once it does, over anything installed earlier.
         #[cfg(target_os = "macos")]

packaging/linux/com.mrgeckosmedia.MidiHarbor.desktop

@@ -4,7 +4,8 @@ Name=Midi Harbor
 Comment=Virtual MIDI ports, hardware, network sessions and Bluetooth MIDI that reconnect by themselves
 Exec=midi-harbor gui
 Icon=com.mrgeckosmedia.MidiHarbor
-StartupWMClass=com.mrgeckosmedia.MidiHarbor
+# On X11 the window's class is argv[0]'s file name; Wayland pairs by the application ID instead.
+StartupWMClass=midi-harbor
 Terminal=false
 Categories=AudioVideo;Audio;Midi;
 Keywords=MIDI;RTP-MIDI;Network MIDI;Bluetooth;