Allow opening Syncthing directly when clicking on tray icon

This might be useful if minimalism is desired or to avoid positioning
issues on Wayland.

README.md

@@ -544,6 +544,9 @@ the appearance settings. That doesn't fix the positioning issue but then it
 looks just like a normal application so not being positioned in the tray area is
 less problematic.
 
+You can also select the window type "None". This disables Syncthing Tray's own UI
+completely and instead opens Syncthing directly when the tray icon is clicked.
+
 ### Workaround broken High-DPI scaling of Plasmoid under X11
 Setting the environment variable `PLASMA_USE_QT_SCALING=1` should fix the
 [issue](https://bugs.kde.org/show_bug.cgi?id=356446) on recent Plasma versions but

syncthingwidgets/settings/appearanceoptionpage.ui

@@ -388,6 +388,11 @@
        <string>Window without titlebar</string>
       </property>
      </item>
+     <item>
+      <property name="text">
+       <string>None - open Syncthing directly</string>
+      </property>
+     </item>
     </widget>
    </item>
    <item row="2" column="0">

tray/gui/traymenu.cpp

@@ -64,6 +64,10 @@ static void moveInside(QPoint &point, const QSize &innerRect, const QRect &outer
 
 void TrayMenu::showUsingPositioningSettings()
 {
+    if (m_windowType == WindowType::None) {
+        widget().showWebUI();
+        return;
+    }
     resize(sizeHint());
     auto pos = Settings::values().appearance.positioning.positionToUse();
     if (pos.has_value()) {
@@ -77,7 +81,7 @@ void TrayMenu::showUsingPositioningSettings()
 
 void TrayMenu::setWindowType(int windowType)
 {
-    if (windowType >= 0 && windowType <= 2) {
+    if (windowType >= 0 && windowType <= 3) {
         setWindowType(static_cast<WindowType>(windowType));
     }
 }
@@ -98,6 +102,8 @@ void TrayMenu::setWindowType(WindowType windowType)
     case WindowType::CustomWindow:
         flags = Qt::Dialog | Qt::CustomizeWindowHint;
         break;
+    case WindowType::None:
+        break;
     }
     setWindowFlags(flags);
 }

tray/gui/traymenu.h

@@ -16,6 +16,7 @@ public:
         Popup,
         NormalWindow,
         CustomWindow,
+        None,
     };
 
     explicit TrayMenu(TrayIcon *trayIcon = nullptr, QWidget *parent = nullptr);