>Do you mean to use MS Rich Textbox Control instead of EditBox on the form? I have never used MS Rich Textbox control. Does it has a Windows Handler property? But it won't work for me here, since I cannot replace the controls on the exiting form. I am trying to add functions to an exiting application. I can add invisible controls on the form to do the additional functions, but not to replace the existing visible controls which will cause too much adjustment.

Yes, that's what I mean. Perhaps, you can add this object on the fly invisible, then put its content to existing editbox. I've never used it myself, so don't know, if it has hWnd or not. I hope it does.