Minor fixes to kiosk mode PR

- UI_FULLSCREEN_WINDOWED -> UI_MAXIMIZED
- Propagate user configuration from old "start windowed" option
- Use FullScreen when a window manager isn't present
- Set disabled control to FullScreen with no window manager

app/gui/main.qml

@@ -20,10 +20,10 @@ ApplicationWindow {
     visibility: {
         if (SystemProperties.hasWindowManager) {
             if (StreamingPreferences.uiDisplayMode == StreamingPreferences.UI_WINDOWED) return "Windowed"
-            else if (StreamingPreferences.uiDisplayMode == StreamingPreferences.UI_FULLSCREEN_WINDOWED) return "Maximized"
+            else if (StreamingPreferences.uiDisplayMode == StreamingPreferences.UI_MAXIMIZED) return "Maximized"
             else if (StreamingPreferences.uiDisplayMode == StreamingPreferences.UI_FULLSCREEN) return "FullScreen"
         } else {
-            return "Maximized"
+            return "FullScreen"
         }
     }