Insert characters at cursor position.

I'm not exactly sure what you are trying to do, but you can get the points where the mouse is located.

Private Sub Text1_MouseMove(Button As Integer, Shift As Integer, X As Single, Y As Single)
Me.Caption = X & ", " & Y
End Sub

Oh yeah, and if your making an HTML Editor, you may have to use a RichTextBox because a regular Textbox has a limit of characters while a RichTextBox doesn't.