QmlProfiler: improve selection behavior in timeline

When selecting ranges in the timeline the selector would sometimes hang
or behave weirdly when moving back. This was due to incorrect logic in
the selection bounds calculation and because the vertical flicking would
steal mouse events.

Change-Id: I14074463422d1d9a0aa8ecd1f88847e7330c9b6b
Reviewed-by: Kai Koehne <kai.koehne@digia.com>
Reviewed-by: Ulf Hermann <ulf.hermann@digia.com>
Reviewed-by: Eike Ziller <eike.ziller@digia.com>

src/plugins/qmlprofiler/qml/MainView.qml

@@ -309,8 +309,11 @@ Rectangle {
         boundsBehavior: Flickable.StopAtBounds
 
         // ScrollView will try to deinteractivate it. We don't want that
-        // as the horizontal flickable is interactive, too.
-        onInteractiveChanged: interactive = true
+        // as the horizontal flickable is interactive, too. We do occasionally
+        // switch to non-interactive ourselves, though.
+        property bool stayInteractive: true
+        onInteractiveChanged: interactive = stayInteractive
+        onStayInteractiveChanged: interactive = stayInteractive
 
         // ***** child items
         TimeMarks {
@@ -429,6 +432,9 @@ Rectangle {
                 onPressed:  {
                     selectionRange.pressedOnCreation();
                 }
+                onCanceled: {
+                    selectionRange.releasedOnCreation();
+                }
                 onPositionChanged: {
                     selectionRange.movedOnCreation();
                 }