Inserts new_text_length bytes of new_text into the contents of the widget, at position position.
Note that the position is in characters, not in bytes. The function updates position to point after the newly inserted text.
the text to append
location of the position text will be inserted at
Inserts new_text_length bytes of new_text into the contents of the widget, at position position.
Note that the position is in characters, not in bytes. The function updates position to point after the newly inserted text.