onInsertText  
  fun onInsertText(connectFlags: <Error class: unknown class> = ConnectFlags(0u), handler: (location: TextIter, text: String, <Error class: unknown class>) -> Unit): <Error class: unknown class>(source)
Emitted to insert text in a GtkTextBuffer.
Insertion actually occurs in the default handler.
Note that if your handler runs before the default handler it must not invalidate the @location iter (or has to revalidate it). The default signal handler revalidates it to point to the end of the inserted text.
See also: method@Gtk.TextBuffer.insert, method@Gtk.TextBuffer.insert_range.
Parameters
connectFlags 
a combination of ConnectFlags
handler
the Callback to connect. Params: location position to insert @text in @textbuffer; text the UTF-8 text to be inserted; len length of the inserted text in bytes