When a data context changes, it should be notified to all descendant controls who inherit the data context. This allows the `SelectingItemsControl` to defer setting the selected item until the `DataContext` has changed for the whole tree.
Renamed `OnDataContextChanging`/`OnDataContextChanged` to `OnDataContextBeginUpdate`/`OnDataContextEndUpdate` because `DataContextChanged` is now called from the property changed notification.
Fixes#507.
Previously it wasn't clear which constructor on `InstancedBinding` must be called for a particular binding mode. Refactored the constructors:
- We now have a single public ctor which takes an `ISubject`, as a subject can be used for all binding modes.
- Instanced bindings with other sources such as single values and `IObservables` are now constructed via static methods which only allow the correct sources for that binding mode
Otherwise if `TextBox.CaretIndex` is set before the `TextBox`'s template is applied then it will be coerced to null on the `TextPresenter` when created as `Text` will still be null at this point.
Previously, if the user overrode `OnAttachedToVisualTree` or `OnDetachedFromVisualTree` and forgot to call the base implementation, the events wouldn't be raised. It's very important that these events get raised so moved the code to raise them to `OnAttachedToVisualTreeCore`/`OnDetachedFromVisualTreeCore`.
Previously, if the user overrode `OnAttachedToLogicalTree` or `OnDetachedFromLogicalTree` and forgot to call the base implementation, the events wouldn't be raised. It's very important that these events get raised so moved the code to raise them to `OnAttachedToLogicalTreeCore`/`OnDetachedFromLogicalTreeCore`.
When a captured control is removed from the visual tree, clear the mouse capture.
Note that our capture logic needs to be improved - it shouldn't be possible to capture a non-visible or non-enabled control. This doesn't address that but it does fix the crash in #1203.
Fixes#1203
Nikita Tsukanov
Steven Kirk
Jeremy Koritzinsky
brandonhood
Dan Walmsley