doc: explain more about acceptedModifiers in PointerDeviceHandler

Having neither a list of all possible modifiers nor a link to
Qt::KeyboardModifier was inconvenient.  Clarify that bitwise OR
results in logical-AND behavior, while having multiple handlers
results in logical-OR behavior, and that a switch statement in JS
allows you do anything you like with modifiers.  Fix the manual test
to test the switch statement and deal with the fact that
point.event.modifiers is undefined: TapHandler can use
eventPoint.modifiers, but any DeviceHandler can use point.modifiers.

Fixes: QTBUG-78234
Change-Id: Iba2a03950aa1279ef454cc76fc8de1b2dab14dfb
Reviewed-by: Venugopal Shivashankar <Venugopal.Shivashankar@qt.io>
Reviewed-by: Jan Arve Sæther <jan-arve.saether@qt.io>

0 files changed, 0 insertions, 0 deletions