Port SelectingItemsBehavior to DataGrid

src/Avalonia.FuncUI/DSL/DataGrid.fs

@@ -1,7 +1,5 @@
 namespace Avalonia.FuncUI.DSL
 
-open Avalonia
-open Avalonia.Controls.Documents
 open Avalonia.Controls.Templates
 open Avalonia.Data
 open Avalonia.Media
@@ -36,6 +34,21 @@ module DataGrid =
 
         static member canUserSortColumns<'t when 't :> DataGrid>(value: bool) : IAttr<'t> =
             AttrBuilder<'t>.CreateProperty<bool>(DataGrid.CanUserSortColumnsProperty, value, ValueNone)
+
+        static member selectedIndex<'t when 't :> DataGrid>(index: int) : IAttr<'t> =
+            AttrBuilder<'t>.CreateProperty<int>(DataGrid.SelectedIndexProperty, index, ValueNone)
+
+        static member selectedItem<'t when 't :> DataGrid>(item: obj) : IAttr<'t> =
+            AttrBuilder<'t>.CreateProperty<obj>(DataGrid.SelectedItemProperty, item, ValueNone)
+
+        static member selection<'t when 't :> DataGrid>(model: DataGridSelectionMode) : IAttr<'t> =
+            AttrBuilder<'t>.CreateProperty<DataGridSelectionMode>(DataGrid.SelectionModeProperty, model, ValueNone)
+
+        static member onSelectedItemChanged<'t when 't :> DataGrid>(func: obj -> unit, ?subPatchOptions) =
+            AttrBuilder<'t>.CreateSubscription<obj>(DataGrid.SelectedItemProperty, func, ?subPatchOptions = subPatchOptions)
+
+        static member onSelectionChanged<'t when 't :> DataGrid>(func: SelectionChangedEventArgs -> unit, ?subPatchOptions) =
+            AttrBuilder<'t>.CreateSubscription<SelectionChangedEventArgs>(DataGrid.SelectionChangedEvent, func, ?subPatchOptions = subPatchOptions)
 
         static member columns (columns: IView list) : IAttr<'t> =
             AttrBuilder<'t>.CreateContentMultiple(

src/Examples/Examples.DataGridPlayground/Program.fs

@@ -28,14 +28,26 @@ type Views =
                     Person("Bob", 22, true)
                 ]
             )
+
+            let selectedItem = ctx.useState None
 
             DockPanel.create [
                 DockPanel.children [
-
+                    TextBlock.create [
+                        TextBlock.dock Dock.Top
+                        TextBlock.margin 10
+                        TextBlock.text $"""Selected: {(selectedItem.Current |> Option.defaultValue (Person("", 0, false))).Name}"""
+                    ]
                     DataGrid.create [
                         DataGrid.dock Dock.Top
                         DataGrid.isReadOnly false
                         DataGrid.items data.Current
+                        DataGrid.onSelectedItemChanged (fun item ->
+                            (match box item with
+                             | null -> None
+                             | :? Person as i -> Some i
+                             | _ -> failwith "Something went horribly wrong!")
+                            |> selectedItem.Set)
 
                         DataGrid.columns [
                             DataGridTextColumn.create [