Exposing the `ContentPresenter.Child` in `ItemsControl.LogicalChildren` was causing problems when detaching and reattaching an `ItemsControl` to the logical tree. Instead, expose the `ContentPresenter` itself in effect meaning that `ItemsControl` has a "container" type just like the controls derived from it.
Fixes#3487
Having a separate subscription to `Items.CollectionChanged` in both `ItemsControl` and `ItemsPresenter` meant that the `ItemsPresenter` sometimes doesn't update itself in time for a selection change, resulting in #3148. Make `ItemsControl` trigger `ItemsPresenter.ItemsChanged` rather than both controls listening to the event separately.
Removed the code that was causing the TreeView problems described in #2944. This code was never actually called except in `TreeView` because a plain `ItemsControl` can't be used with virtualization (it uses untyped `ItemContainerGenerator` so items can't be recycled) and every other derived class derives from SelectingItemsControl which overrides this method and doesn't call the base implementation. In addition there were no unit tests covering this code.
Fixes#2944
During initial layout, `TemplatedParent` is read tens of thousands of times. This being a styled property that used `inherits: true` meant that it was showing up in profiling as taking up a significant amount of time.
Make `TemplatedParent` a direct property so that reading it is a simple property access. This doesn't actually complicate the code much at all as once set the property value doesn't change, so `inherited: true` semantics are not that important.
Can't remember why this was there but it was wrong anway - it wasn't
actually removing the items from the presenter panel. Doesn't seem to
break any unit tests so hope for the best...
Steven Kirk
Dariusz Komosinski
Steven Kirk
Miha Markič
Unknown
sdoroff
Jurjen Biewenga
Nikita Tsukanov