Track screen in the containment when inside an applet

Make the system tray containment update which screen it is on when the
system tray applet is moved.

This fixes notifications if the panel is moved between screens.

REVIEW: 117946

src/plasma/private/containment_p.cpp

@@ -41,6 +41,28 @@ namespace Plasma
 
 const char ContainmentPrivate::defaultWallpaper[] = "org.kde.image";
 
+ContainmentPrivate::ContainmentPrivate(Containment *c):
+    q(c),
+    formFactor(Types::Planar),
+    location(Types::Floating),
+    lastScreen(-1), // never had a screen
+    type(Plasma::Types::NoContainmentType)
+{
+    //if the parent is an applet (i.e we are the systray)
+    //we want to follow screen changed signals from the parent's containment
+    auto appletParent = qobject_cast<Plasma::Applet *>(c->parent());
+    if (appletParent) {
+        QObject::connect(appletParent->containment(), &Containment::screenChanged, c, &Containment::screenChanged);
+    }
+}
+
+Plasma::ContainmentPrivate::~ContainmentPrivate()
+{
+    qDeleteAll(applets);
+    applets.clear();
+}
+
+
 void ContainmentPrivate::addDefaultActions(KActionCollection *actions, Containment *c)
 {
     actions->setConfigGroup("Shortcuts-Containment");

src/plasma/private/containment_p.h

@@ -44,23 +44,10 @@ class Containment;
 class ContainmentPrivate
 {
 public:
-    ContainmentPrivate(Containment *c)
-        : q(c),
-          formFactor(Types::Planar),
-          location(Types::Floating),
-          lastScreen(-1), // never had a screen
-          type(Plasma::Types::NoContainmentType)
-    {
-    }
+    ContainmentPrivate(Containment *c);
 
-    ~ContainmentPrivate()
-    {
-        // qDeleteAll is broken with Qt4.8, delete it by hand
-        while (!applets.isEmpty()) {
-            delete applets.first();
-        }
-        applets.clear();
-    }
+
+    ~ContainmentPrivate();
 
     void triggerShowAddWidgets();
     void checkStatus(Plasma::Types::ItemStatus status);