Gtk.TextView.prototype.set_buffer

function set_buffer(buffer:Gtk.TextBuffer):void {
    // Gjs wrapper for gtk_text_view_set_buffer()
}

Sets buffer as the buffer being displayed by text_view. The previous buffer displayed by the text view is unreferenced, and a reference is added to buffer. If you owned a reference to buffer before passing it to this function, you must remove that reference yourself; Gtk.TextView will not "adopt" it.