Deliver mouse press and release events on X11 also when dragging

We generally assume that for every mouse press we also get a mouse
release eventually. The event filter installed by QBasicDrag broke this
assumption as it didn't take care of filtering mouse press and mouse
release events symmetrically. We cannot immediately pass on the release
event as that would mean a release event is generated from a press
event (via the blocking drag call), which breaks assumptions in other
places.

Change-Id: If7e48c7dc0ef5265bed4f9a9366a7606ec875d93
Task-number: QTBUG-46361
Reviewed-by: Friedemann Kleint <Friedemann.Kleint@theqtcompany.com>
Reviewed-by: Gatis Paeglis <gatis.paeglis@digia.com>

1 files changed, 3 insertions, 3 deletions

diff --git a/src/gui/kernel/qsimpledrag.cpp b/src/gui/kernel/qsimpledrag.cpp
index 6e574d82e4..b02f1dd8bd 100644
--- a/src/gui/kernel/qsimpledrag.cpp
+++ b/src/gui/kernel/qsimpledrag.cpp
@@ -149,7 +149,7 @@ bool QBasicDrag::eventFilter(QObject *o, QEvent *e)
         {
             QPoint nativePosition = getNativeMousePos(e, o);
             move(nativePosition);
-            return true; // Eat all mouse events
+            return true; // Eat all mouse move events
         }
         case QEvent::MouseButtonRelease:
             disableEventFilter();
@@ -160,8 +160,8 @@ bool QBasicDrag::eventFilter(QObject *o, QEvent *e)
                 cancel();
             }
             exitDndEventLoop();
-            return true; // Eat all mouse events
-        case QEvent::MouseButtonPress:
+            QCoreApplication::postEvent(o, new QMouseEvent(*static_cast<QMouseEvent *>(e)));
+            return true; // defer mouse release events until drag event loop has returned
         case QEvent::MouseButtonDblClick:
         case QEvent::Wheel:
             return true;