Bug 305: Disable setting default browser on Windows

Until we can pull in upstream changes to fix breakage in setting
the Mullvad Browser as default in Windows 10/11 we're disabling
the ability to do so via about:preferences as well as via the
startup query dialog

browser/components/preferences/main.js

@@ -1765,7 +1765,10 @@ var gMainPane = {
         "@mozilla.org/xre/directory-provider;1"
       ].getService(Ci.nsIXREDirProvider);
       // Flatpak does not support setting nor detection of default browser
-      if (!shellSvc || isInFlatpak || xreDirProvider.isPortableMode) {
+      // Mullvad Bug 298: the ability to set Mullvad as the default browser in
+      // Windows is currently not functioning so hide the DOM Element containing
+      // default browser settings on non-portable Windows installs as well
+      if (!shellSvc || isInFlatpak || xreDirProvider.isPortableMode || AppConstants.platform == "win") {
         defaultBrowserBox.hidden = true;
         return;
       }

browser/components/shell/ShellService.sys.mjs

@@ -92,6 +92,13 @@ let ShellServiceInternal = {
    */
   _checkedThisSession: false,
   get shouldCheckDefaultBrowser() {
+    // Mullvad Bug 298: the ability to set Mullvad as the default browser in
+    // Windows is currently not functioning so in lieu of overwriting user prefs
+    // or shipping a new default return early here
+    if(AppConstants.platform == "win") {
+      return false;
+    }
+
     // If we've already checked, the browser has been started and this is a
     // new window open, and we don't want to check again.
     if (this._checkedThisSession) {