opt: stop show tray icon in root mode

src/core_main.rs

@@ -188,8 +188,14 @@ pub fn core_main() -> Option<Vec<String>> {
             #[cfg(target_os = "linux")]
             {
                 let handler = std::thread::spawn(move || crate::start_server(true));
+                // Show the tray in linux only when current user is a normal user
+                // [Note]
+                // As for GNOME, the tray cannot be shown in user's status bar.
+                // As for KDE, the tray can be shown without user's theme.
+                if !crate::platform::is_root() {
                     crate::tray::start_tray();
-                // revent server exit when encountering errors from tray
+                }
+                // prevent server exit when encountering errors from tray
                 hbb_common::allow_err!(handler.join());
             }
         } else if args[0] == "--import-config" {

src/tray.rs

@@ -150,6 +150,13 @@ fn get_default_app_indicator() -> Option<AppIndicator> {
     match std::fs::File::create(icon_path.clone()) {
         Ok(mut f) => {
             f.write_all(icon).unwrap();
+            // set .png icon file to be writable
+            // this ensures successful file rewrite when switching between x11 and wayland.
+            let mut perm = f.metadata().unwrap().permissions();
+            if perm.readonly() {
+                perm.set_readonly(false);
+                f.set_permissions(perm).unwrap();
+            }
         }
         Err(err) => {
             error!("Error when writing icon to {:?}: {}", icon_path, err);