deleteInteractive 
  open fun deleteInteractive(startIter: TextIter, endIter: TextIter, defaultEditable: Boolean): Boolean(source)
Deletes all editable text in the given range.
Calls method@Gtk.TextBuffer.delete for each editable sub-range of [@start,@end). @start and @end are revalidated to point to the location of the last deleted range, or left untouched if no text was deleted.
Return
whether some text was actually deleted
Parameters
startIter 
start of range to delete
endIter 
end of range
defaultEditable 
whether the buffer is editable by default