The accessibility code for notifying focus changes related to a
table/tree view was iterating over all items to find the focused one,
which for a very large number of items could cause a major slowdown
and UI freeze. This patch avoids the issue by removing the loop and
implementing the focusChild() method in the table/tree accessibility
classes.
Fixes: QTBUG-100997
Pick-to: 6.2 6.3 5.15
Change-Id: I04c847a5e65223b7a93ab82363feb32e1ebab9f3
Reviewed-by: Volker Hilsheimer <volker.hilsheimer@qt.io>
4114a0ea75