This patch avoids synthesizing mouse messages in the QPA for touch/pen
input, and lets the GUI do mouse event synthesis for unhandled touch/pen
events, if required, like in other platforms. This requires a workaround
to avoid breaking drag and drop with touch/pen (or making it worse). DnD
on Windows is based on the DoDragDrop() Win32 API, which does not work
with touch/pen input, which in some cases cause a DnD operation started
with touch/pen to hang until the mouse is moved. To avoid it we process
pointer messages for touch/pen and generate mouse input through
SendInput() to trigger DoDragDrop(), which then seems to work as
expected.
So now we inform QtGui that the Windows platform no longer sends
synth-mouse events after tablet events (unsetting the flag added in
f931e5e72d); this completes what was
attempted in 8ada0633cd.
Fixes: QTBUG-106368
Fixes: QTBUG-57577
Fixes: QTBUG-100788
Task-number: QTBUG-77414
Task-number: QTBUG-104594
Pick-to: 6.4 6.3 6.2
Change-Id: I46db3c74be2a95cf2d94ba930398e58dc930d2db
Reviewed-by: Shawn Rutledge <shawn.rutledge@qt.io>
31e7790102