diff --git a/src/Avalonia.Controls.DataGrid/Collections/DataGridCollectionView.cs b/src/Avalonia.Controls.DataGrid/Collections/DataGridCollectionView.cs
index 4b4203ba40..92734b128d 100644
--- a/src/Avalonia.Controls.DataGrid/Collections/DataGridCollectionView.cs
+++ b/src/Avalonia.Controls.DataGrid/Collections/DataGridCollectionView.cs
@@ -927,7 +927,7 @@ namespace Avalonia.Collections
         /// <remarks>
         /// <p>
         /// Clear a sort criteria by assigning SortDescription.Empty to this property.
-        /// One or more sort criteria in form of <seealso cref="SortDescription"/>
+        /// One or more sort criteria in form of <seealso cref="DataGridSortDescription"/>
         /// can be used, each specifying a property and direction to sort by.
         /// </p>
         /// </remarks>
@@ -4312,4 +4312,4 @@ namespace Avalonia.Collections
             }
         }       
     }
-}
\ No newline at end of file
+}
diff --git a/src/Avalonia.Controls/Grid.cs b/src/Avalonia.Controls/Grid.cs
index b51583d8b3..90a27d0b31 100644
--- a/src/Avalonia.Controls/Grid.cs
+++ b/src/Avalonia.Controls/Grid.cs
@@ -177,6 +177,17 @@ namespace Avalonia.Controls
             return element.GetValue(RowSpanProperty);
         }
 
+
+        /// <summary>
+        /// Gets the value of the IsSharedSizeScope attached property for a control.
+        /// </summary>
+        /// <param name="element">The control.</param>
+        /// <returns>The control's IsSharedSizeScope value.</returns>
+        public static bool GetIsSharedSizeScope(AvaloniaObject element)
+        {
+            return element.GetValue(IsSharedSizeScopeProperty);
+        }
+
         /// <summary>
         /// Sets the value of the Column attached property for a control.
         /// </summary>
@@ -217,6 +228,16 @@ namespace Avalonia.Controls
             element.SetValue(RowSpanProperty, value);
         }
 
+        /// <summary>
+        /// Sets the value of IsSharedSizeScope property for a control.
+        /// </summary>
+        /// <param name="element">The control.</param>
+        /// <param name="value">The IsSharedSizeScope value.</param>
+        public static void SetIsSharedSizeScope(AvaloniaObject element, bool value)
+        {
+            element.SetValue(IsSharedSizeScopeProperty, value);
+        }
+
         /// <summary>
         /// Gets the result of the last column measurement.
         /// Use this result to reduce the arrange calculation.
diff --git a/src/Avalonia.Controls/Platform/InProcessDragSource.cs b/src/Avalonia.Controls/Platform/InProcessDragSource.cs
index f8ae9f4249..0918da1a90 100644
--- a/src/Avalonia.Controls/Platform/InProcessDragSource.cs
+++ b/src/Avalonia.Controls/Platform/InProcessDragSource.cs
@@ -147,7 +147,10 @@ namespace Avalonia.Platform
                 e.Handled = true;
             }
             else if (e.Key == Key.LeftCtrl || e.Key == Key.RightCtrl || e.Key == Key.LeftAlt || e.Key == Key.RightAlt)
-                RaiseEventAndUpdateCursor(RawDragEventType.DragOver, _lastRoot, _lastPosition, e.Modifiers);
+            {
+                if (_lastRoot != null)
+                    RaiseEventAndUpdateCursor(RawDragEventType.DragOver, _lastRoot, _lastPosition, e.Modifiers);
+            }
         }
 
         private void ProcessMouseEvents(RawMouseEventArgs e)