Problem:
Currently calling Track::EnsureVisible() also sets the track as focus.
In Audacity 2.3.3 the timing of the code to set the focus was changed. Rather than a direct call, an event is queued, and then the focus is set. This has changed the timing of the focus event which is sent with respect to other focus and name change events. In particular in the case of toggling the selectness of the focused track, this moved the focus event to be after the name change event.
These changes only had an effect on NVDA - Jaws and Narrator were unaffected.
The introduction of this bug has highlighted an existing problem.
1. There are a small number of existing cases where a track needs to be visible, but where it is already the focus, and so setting the focus is unnecessary. For example, pressing Enter to toggle whether a track is selected.
2. Some of the Audacity code which calls EnsureVisible() is written with the assumption that EnsureVisible() doesn't set the focus, and so there are unnecessary focus events. Whilst other code which calls EnsureVisible() assumes that it also sets the focus. Confusion.
The Fix:
Remove the setting of focus from within Track::EnsureVisible(), and so remove the unnecessary focus events.
Calls to set the focus were added before calls to EnsureVisible where the code was relying on EnsureVisible to set the focus. In TrackPanel::ProcessUIHandleResult, and TrackPanel::OnMouseEvent, I wasn't sure if the focus needed to be set, so called it anyway to ensure that the behaviour did not change.
So I would like to remove the setting of focus from within Track::EnsureVisible(), and add explicit calls to set the focus where necessary.
I think this would make the code clearer, remove unnecessary calls to set the focus, and make it easier to keep NVDA happy.
... Let the window respond to an undo manager event instead, whenever there
is a push or modify
Maybe this makes a few unnecessary redraws that did not happen before. If
that is important, then we should figure out how to put the logic for eliding
the redraw into ProjectWindow, and the extra information needed for the
decision into the events, but not make intrusions in other code all over the
place.
... Problem involves sequence in which event handlers are done, and started at
commit 278509a which updated track Y coordinates in a handler.
Solution is to delay the updating of scrollbars further, using CallAfter.
Also remove one unnecessary call to ProjectWindow::FixScrollbars() because
ProjectWindow::HandleResize follows it and includes scrollbar update already.
