Improving / Fixing Selection Behavior (ItemSelectionEventTriggers)

[ArchLeaders]

I have been attempting to fix a bug in Xaml.Behaviors that caused press events on draggable elements implementing ISelectable to be cancelled (e.Handled = true) early. (wieslawsoltes/Xaml.Behaviors#318)

In that library, it was an intentional decision to avoid items being deselected when starting a drag event. (wieslawsoltes/Xaml.Behaviors@04b9138)

However, the root of the issue is Avalonia always selecting on the press event rather than waiting for release.

In Rider, for example, selecting a node that is already selected does not deselect the other nodes until releasing.

I have updated the selection behavior to act more like Rider here and plan to make a PR.

Since this is technically a feature, not a bug fix, I was hoping to discuss the change with the core team before making a PR.

And, if this is not something Avalonia can do, hopefully have some insight on the correct way to solve this problem.

[ArchLeaders]

Note: My implementation currently has the side effect of breaking Ctrl+Click to add to the selection (selects on press and deselects on release).

[ArchLeaders]

Fixed in ArchLeaders@0103039