Make `SelectionModelChildrenRequestedEventArgs.Children` an observable, so that the we can react to the children collection object changing, as well as the children inside the collection changing.
Upstream issue: https://github.com/microsoft/microsoft-ui-xaml/issues/2404
Top-level controls cannot have a `Bounds` offset, and their `(Min)/(Max)/Width` and `(Min)/(Max)/Height` reflects the client size of the actual window, so don't need to be applied at the layout level.
Fixes#3784
So that the event can be marked as handled if necessary. Mark the event as handled in `AutoCompleteBox`, `ComboBox` and `DatePicker`, but _not_ `ContextMenu`. Fixes#3760.
The API for `ScrollChangedEventArgs` is different to WPF's here, because:
- Avalonia's `ScrollViewer` exposes `Extent`, `Offset` and `Viewport` as `Size`/`Vector` structs whereas WPF exposes separate `double` values for the X and Y components for each of these
- The current values are not included in the event args: then can easily be read from the `sender`
- UWP doesn't expose these values at all
For non-logical scrolling:
- Use 16 for small scroll size (value taken from WPF)
- Use viewport size for large scroll
For logical scrolling, use the `ScrollSize`/`PageScrollSize` defined on `ILogicalScrollable`. Note that this required a small breaking change to `ILogicalScrollable`.
Fixed#3245
- Don't use Rx in the styling system. Instead introduces `IStyleActivator` which is like an `IObservable<bool>`-lite in order to cut down on allocations.
- #nullable enable on touched files
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
Dan Walmsley
Steven Kirk
Dariusz Komosinski
Deadpikle
Benedikt Schroeder
Joe Clapis