fixed paste into RichTextBox in MultiFormatTextBox

MultiTerm.Wpf.CustomControl/MultiFormatTextBox/MultiFormatTextBox.cs

@@ -114,6 +114,7 @@ public class MultiFormatTextBox : Control
             this.richTextBox.PreviewKeyDown += RichTextBox_KeyDown;
             this.richTextBox.PreviewTextInput += RichTextBox_PreviewTextInput;
             this.richTextBox.SelectionChanged += RichTextBox_SelectionChanged;
+            DataObject.AddPastingHandler(this.richTextBox, OnRtbPaste);
         }
         else
         {
@@ -352,6 +353,24 @@ public class MultiFormatTextBox : Control
         this.InsertCharacterAtCaretPositionIntoCurrentMultiFormatString(e.Text);
     }
 
+    private void OnRtbPaste(object sender, DataObjectPastingEventArgs e)
+    {
+        // get pasted data
+        if (e.DataObject.GetDataPresent(typeof(string)))
+        {
+            // get data as string
+            var text = (string)e.DataObject.GetData(typeof(string));
+            // insert each character seperately
+            foreach (var character in text)
+            {
+                this.InsertCharacterAtCaretPositionIntoCurrentMultiFormatString(character.ToString());
+            }
+        }
+
+        // cancel pasting
+        e.CancelCommand();
+    }
+
     private void InsertCharacterAtCaretPositionIntoCurrentMultiFormatString(string text)
     {
         var caretPosition = this.GetRtbCaretPosition();