Support submenus in context menu for systray icon

Reviewers: #plasma, graesslin, davidedmundson

Reviewed By: #plasma, davidedmundson

Subscribers: broulik, davidedmundson, plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D9643

src/platformtheme/kdeplatformsystemtrayicon.cpp

@@ -47,6 +47,11 @@ QPlatformMenuItem *SystemTrayMenu::createMenuItem() const
     return new SystemTrayMenuItem();
 }
 
+QPlatformMenu *SystemTrayMenu::createSubMenu() const
+{
+    return new SystemTrayMenu();
+}
+
 void SystemTrayMenu::insertMenuItem(QPlatformMenuItem *menuItem, QPlatformMenuItem *before)
 {
     if (SystemTrayMenuItem *ours = qobject_cast<SystemTrayMenuItem*>(menuItem)) {

src/platformtheme/kdeplatformsystemtrayicon.h

@@ -47,6 +47,7 @@ public:
     void syncSeparatorsCollapsible(bool enable) override;
     quintptr tag() const override;
     QPlatformMenuItem *createMenuItem() const override;
+    QPlatformMenu *createSubMenu() const override;
 
     QMenu *menu() const;