gtk-text-buffer-insert-interactive (buffer iter text len default-editable)
Whether text was actually inserted.
Like the function gtk-text-buffer-insert, but the insertion will not occur if iter is at a non-editable location in the buffer. Usually you want to prevent insertions at ineditable locations if the insertion results from a user action (is interactive).
default-editable indicates the editability of text that does not have a tag affecting editability applied to it. Typically the result of the function gtk-text-view-get-editable is appropriate here.