Add xmlns definitions, fix references & trim some warnings.

samples/ControlCatalog/Pages/DataGridPage.xaml

@@ -1,6 +1,7 @@
 <UserControl xmlns="https://github.com/avaloniaui"
              xmlns:local="clr-namespace:ControlCatalog.Models;assembly=ControlCatalog"
-             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml">
+             xmlns:x="http://schemas.microsoft.com/winfx/2006/xaml"
+             x:Class="ControlCatalog.Pages.DataGridPage">
   <UserControl.Resources>
     <local:GDPValueConverter x:Key="GDPConverter" />
   </UserControl.Resources>

src/Avalonia.Controls.DataGrid/Collections/CollectionView.cs

@@ -3360,7 +3360,7 @@ namespace Avalonia.Collections
                 addIndex);
 
             // next check if we need to add an item into the current group
-            bool needsGrouping = false;
+            // bool needsGrouping = false;
             if (Count == 1 && GroupDescriptions.Count > 0)
             {
                 // if this is the first item being added
@@ -3387,7 +3387,7 @@ namespace Avalonia.Collections
                 // otherwise, we need to validate that it is within the current page.
                 if (PageSize == 0 || (PageIndex + 1) * PageSize > leafIndex)
                 {
-                    needsGrouping = true;
+                    //needsGrouping = true;
 
                     int pageStartIndex = PageIndex * PageSize;
 

src/Avalonia.Controls.DataGrid/DataGrid.cs

@@ -746,11 +746,12 @@ namespace Avalonia.Controls
 
         static DataGrid()
         {
-            AffectsMeasure(
+            AffectsMeasure<DataGrid>(
                 ColumnHeaderHeightProperty, 
                 HorizontalScrollBarVisibilityProperty,
                 VerticalScrollBarVisibilityProperty);
-            PseudoClass(IsValidProperty, x => !x, ":invalid");
+
+            PseudoClass<DataGrid, bool>(IsValidProperty, x => !x, ":invalid");
 
             ItemsProperty.Changed.AddClassHandler<DataGrid>(x => x.OnItemsPropertyChanged);
             CanUserResizeColumnsProperty.Changed.AddClassHandler<DataGrid>(x => x.OnCanUserResizeColumnsChanged);

src/Avalonia.Controls.DataGrid/DataGridColumnHeader.cs

@@ -340,7 +340,7 @@ namespace Avalonia.Controls
                 && OwningGrid.DataConnection.SortDescriptions != null)
             {
                 DataGrid owningGrid = OwningGrid;
-                bool desending;
+
                 AvaloniaSortDescription newSort;
 
                 KeyboardHelper.GetMetaKeyState(inputModifiers, out bool ctrl, out bool shift);

src/Avalonia.Controls.DataGrid/DataGridRows.cs

@@ -2505,7 +2505,7 @@ namespace Avalonia.Controls
                     double indent;
                     for (int i = 0; i < groupLevelCount; i++)
                     {
-                        DataGridRowGroupHeader rowGroupHeader = null;
+                        //DataGridRowGroupHeader rowGroupHeader = null;
                         indent = DATAGRID_defaultRowGroupSublevelIndent;
                         //if (i < RowGroupHeaderStyles.Count && RowGroupHeaderStyles[i] != null)
                         //{

src/Avalonia.Controls.DataGrid/Primitives/DataGridDetailsPresenter.cs

@@ -42,7 +42,7 @@ namespace Avalonia.Controls.Primitives
 
         public DataGridDetailsPresenter()
         {
-            AffectsMeasure(ContentHeightProperty);
+            AffectsMeasure<DataGridDetailsPresenter>(ContentHeightProperty);
         }
 
         /// <summary>

src/Avalonia.Controls.DataGrid/Properties/AssemblyInfo.cs

@@ -9,4 +9,6 @@ using Avalonia.Metadata;
 [assembly: InternalsVisibleTo("Avalonia.DesignerSupport")]
 
 [assembly: XmlnsDefinition("https://github.com/avaloniaui", "Avalonia")]
-[assembly: XmlnsDefinition("https://github.com/avaloniaui", "Avalonia.Controls.DataGrid")]
+[assembly: XmlnsDefinition("https://github.com/avaloniaui", "Avalonia.Controls")]
+[assembly: XmlnsDefinition("https://github.com/avaloniaui", "Avalonia.Controls.Primitives")]
+[assembly: XmlnsDefinition("https://github.com/avaloniaui", "Avalonia.Controls.Collections")]

src/Avalonia.Themes.Default/Avalonia.Themes.Default.csproj

@@ -7,6 +7,7 @@
     <ProjectReference Include="..\Avalonia.Animation\Avalonia.Animation.csproj" />
     <ProjectReference Include="..\Avalonia.Base\Avalonia.Base.csproj" />
     <ProjectReference Include="..\Avalonia.Controls\Avalonia.Controls.csproj" />
+    <ProjectReference Include="..\Avalonia.Controls.DataGrid\Avalonia.Controls.DataGrid.csproj" />
     <ProjectReference Include="..\Avalonia.Input\Avalonia.Input.csproj" />
     <ProjectReference Include="..\Avalonia.Interactivity\Avalonia.Interactivity.csproj" />
     <ProjectReference Include="..\Avalonia.Layout\Avalonia.Layout.csproj" />