fix: close #1406

src/Shared/HandyControl_Shared/Controls/Input/TextBox.cs

@@ -9,6 +9,11 @@ public class TextBox : System.Windows.Controls.TextBox
     {
         CommandBindings.Add(new CommandBinding(ControlCommands.Clear, (s, e) =>
         {
+            if (IsReadOnly)
+            {
+                return;
+            }
+
             SetCurrentValue(TextProperty, string.Empty);
         }));
     }