Tablet input not processed (fix included)

Issue initially reported here.

Hovering over some text elements with the tablet causes the hover state to get locked, buttons become unclickable. Clicking away to the side without any text elements solves the hover state getting locked.

The only way of using the affected buttons is clicking in the part of the button which does not contain any text labels.

Steps to reproduce:
Reproducion steps are in the initial issue above.

Attachments:
Attached two videos showing the problem. Video haruna-80 shows it running fine on Qt 5.14.0 and haruna-86 shows the bug on Qt 5.15.2

Possibly related issues:

• QTBUG-96782 (fixed with solution below)
• QTBUG-95357 (fixed with solution below)
• QTBUG-93947 (not tested)

The fix:
Looks like somewhere in Qt 5.15.0 development from this commit,
in file: qtdeclarative/src/quick/items/qquickwindow.cpp
The problematic function QQuickWindow::tabletEvent was made that runs deliverPointerEvent (line 2256).
The deliverPointerEvent function is incomplete and eats the tablet stylus input.

Removing that line solves all of my reported problems in the initial issue. Testing with the 2 above related issues shows that they are also fixed by this.

Conclusion:
Temporary removal of the problematic function or complete implementation of deliverPointerEvent is required as without this solution, many apps using Qt 5.15.2 are very difficult to use with a graphics tablet. It is very inconvenient, when the tablet is used as a main pointer device instead of a mouse.