make TabletMove hover events conditional on QWidget::tabletTracking

This adds the tabletTracking property in the same way that mouseTracking already
existed: there is a WA_TabletTracking attribute, and a TabletTrackingChange event
to notify when it changes.  So for widget applications it's an opt-in feature.
QtQuick applications don't yet make use of tablet events, but when they do
in the future, we don't yet have a mechanism to turn the move events off;
it remains to be seen whether that will be necessary.

[ChangeLog][QtWidget] QWidget now has a tabletTracking property, analogous
to mouseTracking, which will enable TabletMove events while the stylus is
hovering, even if no button is pressed.  This allows applications to show
feedback based on the other tablet event properties such as rotation and tilt.

Task-number: QTBUG-26116
Change-Id: Ie96e8acad882b167e967796cdd17f1ad747a2771
Reviewed-by: Andy Shaw <andy.shaw@qt.io>

1 files changed, 2 insertions, 0 deletions

diff --git a/src/corelib/global/qnamespace.h b/src/corelib/global/qnamespace.h
index c3833c6bd1..da44c01594 100644
--- a/src/corelib/global/qnamespace.h
+++ b/src/corelib/global/qnamespace.h
@@ -472,6 +472,8 @@ public:
 
         WA_AlwaysStackOnTop = 128,
 
+        WA_TabletTracking = 129,
+
         // Add new attributes before this line
         WA_AttributeCount
     };