Problem in cursor movement when the text is entered in textbox?

Textbox textwrap property is set to wrap.

My scenario is enter the text in textbox from SIP. When cursor reaches almost at the end of line may be 3 or 4 char left for line change just enter space so that it should came to next 开发者_如何转开发line. But after pressing space 4 or 5 time or more the cursor will not come to next line moreover it will not shown . It will come to next line when i enter some char.

I think it should came to next line because user may want to enter some space. is this can be fixed.

The other property you need to set on the TextBox is AcceptsReturn to true.