Fix screen handling for child windows.

Change the semantics of QWindowPrivate::screen to contain the screen of
top level window only. Child windows always return the screen of their
toplevel window by recursing up.

The QPA plugins then no longer need to report screen changes for child
windows.

Change setScreen() accordingly, bail out for child windows, and
emit screenChanged() recursively.

Also add a check to setParent() preventing screen changes.

Task-number: QTBUG-36659
Change-Id: I19c8e12217cba1513e947a027f2492abc7b98816
Reviewed-by: Shawn Rutledge <shawn.rutledge@digia.com>
Reviewed-by: Laszlo Agocs <laszlo.agocs@digia.com>

1 files changed, 7 insertions, 3 deletions

diff --git a/src/gui/kernel/qwindow_p.h b/src/gui/kernel/qwindow_p.h
index 4305edea51..0c58745735 100644
--- a/src/gui/kernel/qwindow_p.h
+++ b/src/gui/kernel/qwindow_p.h
@@ -95,7 +95,7 @@ public:
         , modality(Qt::NonModal)
         , blockedByModalWindow(false)
         , transientParent(0)
-        , screen(0)
+        , topLevelScreen(0)
 #ifndef QT_NO_CURSOR
         , cursor(Qt::ArrowCursor)
         , hasCursor(false)
@@ -131,7 +131,11 @@ public:
     void updateVisibility();
     void _q_clearAlert();
 
-    void setScreen(QScreen *newScreen, bool recreate);
+    bool windowRecreationRequired(QScreen *newScreen) const;
+    void setTopLevelScreen(QScreen *newScreen, bool recreate);
+    void connectToScreen(QScreen *topLevelScreen);
+    void disconnectFromScreen();
+    void emitScreenChangedRecursion(QScreen *newScreen);
 
     virtual void clearFocusObject();
 
@@ -165,7 +169,7 @@ public:
     bool blockedByModalWindow;
 
     QPointer<QWindow> transientParent;
-    QScreen *screen;
+    QScreen *topLevelScreen;
 
 #ifndef QT_NO_CURSOR
     QCursor cursor;