Gtk.Editable::insert-text

function callback(editable, new_text:String, new_text_length:Number, position:Number, ):void;

This signal is emitted when text is inserted into the widget by the user. The default handler for this signal will normally be responsible for inserting the text, so by connecting to this signal and then stopping the signal with GObject.signal_stop_emission, it is possible to modify the inserted text, or prevent it from being inserted entirely.

editable: instance of Gtk.Editable that is emitting the signal
new_text: the new text to insert
new_text_length: the length of the new text, in bytes, or -1 if new_text is nul-terminated
position: the position, in characters, at which to insert the new text. this is an in-out parameter. After the signal emission is finished, it should point after the newly inserted text.