DataGrid selection refactoring (#13848)

src/Avalonia.Controls.DataGrid/DataGrid.cs

@@ -1828,12 +1828,6 @@ namespace Avalonia.Controls
             private set;
         }
 
-        internal bool UpdatedStateOnMouseLeftButtonDown
-        {
-            get;
-            set;
-        }
-
         /// <summary>
         /// Indicates whether or not to use star-sizing logic.  If the DataGrid has infinite available space,
         /// then star sizing doesn't make sense.  In this case, all star columns grow to a predefined size of

src/Avalonia.Controls.DataGrid/DataGridCell.cs

@@ -189,8 +189,6 @@ namespace Avalonia.Controls
                     {
                         e.Handled = handled;
                     }
-
-                    OwningGrid.UpdatedStateOnMouseLeftButtonDown = true;
                 }
             }
             else if (e.GetCurrentPoint(this).Properties.IsRightButtonPressed)

src/Avalonia.Controls.DataGrid/DataGridRow.cs

@@ -771,14 +771,6 @@ namespace Avalonia.Controls
             if (OwningGrid != null)
             {
                 OwningGrid.IsDoubleClickRecordsClickOnCall(this);
-                if (OwningGrid.UpdatedStateOnMouseLeftButtonDown)
-                {
-                    OwningGrid.UpdatedStateOnMouseLeftButtonDown = false;
-                }
-                else
-                {
-                    e.Handled = OwningGrid.UpdateStateOnMouseLeftButtonDown(e, -1, Slot, false);
-                }
             }
         }
 

src/Avalonia.Controls.DataGrid/DataGridRowHeader.cs

@@ -195,7 +195,6 @@ namespace Avalonia.Controls.Primitives
                     Debug.Assert(sender is DataGridRowHeader);
                     Debug.Assert(sender == this);
                     e.Handled = OwningGrid.UpdateStateOnMouseLeftButtonDown(e, -1, Slot, false);
-                    OwningGrid.UpdatedStateOnMouseLeftButtonDown = true;
                 }
             }
             else if (e.GetCurrentPoint(this).Properties.IsRightButtonPressed)