QQuickControl: Accept all the mouse events by default

Controls are mouse-opaque items in the sense that, if
the control doesn't do anything with the mouse (or touch)
event, there's no need to propagate it further. This avoids
issues with controls like ToolBar, where clicking on its
background may send the mouse event to an item below it.

Change-Id: Ib3c95a55db2abfd6a13333f4b0187852a656ec03
Reviewed-by: Gabriel de Dietrich <gabriel.dedietrich@theqtcompany.com>
Reviewed-by: J-P Nurmi <jpnurmi@theqtcompany.com>

src/controls/qquickbutton.cpp

@@ -229,14 +229,12 @@ void QQuickButton::mousePressEvent(QMouseEvent *event)
     QQuickControl::mousePressEvent(event);
     setPressed(true);
     emit pressed();
-    event->accept();
 }
 
 void QQuickButton::mouseMoveEvent(QMouseEvent *event)
 {
     QQuickControl::mouseMoveEvent(event);
     setPressed(contains(event->pos()));
-    event->accept();
 }
 
 void QQuickButton::mouseReleaseEvent(QMouseEvent *event)
@@ -251,7 +249,6 @@ void QQuickButton::mouseReleaseEvent(QMouseEvent *event)
     } else {
         emit canceled();
     }
-    event->accept();
 }
 
 void QQuickButton::mouseUngrabEvent()

src/controls/qquickcontrol.cpp

@@ -454,6 +454,21 @@ void QQuickControl::setContentItem(QQuickItem *item)
     }
 }
 
+void QQuickControl::mousePressEvent(QMouseEvent *event)
+{
+    event->accept();
+}
+
+void QQuickControl::mouseMoveEvent(QMouseEvent *event)
+{
+    event->accept();
+}
+
+void QQuickControl::mouseReleaseEvent(QMouseEvent *event)
+{
+    event->accept();
+}
+
 void QQuickControl::geometryChanged(const QRectF &newGeometry, const QRectF &oldGeometry)
 {
     Q_D(QQuickControl);

src/controls/qquickcontrol_p.h

@@ -126,6 +126,9 @@ Q_SIGNALS:
 protected:
     QQuickControl(QQuickControlPrivate &dd, QQuickItem *parent);
 
+    void mousePressEvent(QMouseEvent *event) Q_DECL_OVERRIDE;
+    void mouseMoveEvent(QMouseEvent *event) Q_DECL_OVERRIDE;
+    void mouseReleaseEvent(QMouseEvent *event) Q_DECL_OVERRIDE;
     void geometryChanged(const QRectF &newGeometry, const QRectF &oldGeometry) Q_DECL_OVERRIDE;
 
     virtual void mirrorChange();

src/controls/qquickscrollbar.cpp

@@ -262,7 +262,6 @@ void QQuickScrollBar::mousePressEvent(QMouseEvent *event)
     if (d->offset < 0 || d->offset > d->size)
         d->offset = d->size / 2;
     setPressed(true);
-    event->accept();
 }
 
 void QQuickScrollBar::mouseMoveEvent(QMouseEvent *event)
@@ -270,7 +269,6 @@ void QQuickScrollBar::mouseMoveEvent(QMouseEvent *event)
     Q_D(QQuickScrollBar);
     QQuickControl::mouseMoveEvent(event);
     setPosition(qBound(0.0, positionAt(event->pos()) - d->offset, 1.0 - d->size));
-    event->accept();
 }
 
 void QQuickScrollBar::mouseReleaseEvent(QMouseEvent *event)
@@ -280,7 +278,6 @@ void QQuickScrollBar::mouseReleaseEvent(QMouseEvent *event)
     setPosition(qBound(0.0, positionAt(event->pos()) - d->offset, 1.0 - d->size));
     d->offset = 0.0;
     setPressed(false);
-    event->accept();
 }
 
 qreal QQuickScrollBar::positionAt(const QPoint &point) const

src/controls/qquickslider.cpp

@@ -499,7 +499,6 @@ void QQuickSlider::mousePressEvent(QMouseEvent *event)
     QQuickControl::mousePressEvent(event);
     d->pressPoint = event->pos();
     setPressed(true);
-    event->accept();
 }
 
 void QQuickSlider::mouseMoveEvent(QMouseEvent *event)
@@ -518,7 +517,6 @@ void QQuickSlider::mouseMoveEvent(QMouseEvent *event)
             pos = d->snapPosition(pos);
         d->setPosition(pos);
     }
-    event->accept();
 }
 
 void QQuickSlider::mouseReleaseEvent(QMouseEvent *event)
@@ -534,7 +532,6 @@ void QQuickSlider::mouseReleaseEvent(QMouseEvent *event)
         setKeepMouseGrab(false);
     }
     setPressed(false);
-    event->accept();
 }
 
 void QQuickSlider::mouseUngrabEvent()