Gtk.TextBuffer.prototype.place_cursor

function place_cursor(where:Gtk.TextIter):void {
    // Gjs wrapper for gtk_text_buffer_place_cursor()
}

This function moves the "insert" and "selection_bound" marks simultaneously. If you move them to the same place in two steps with Gtk.TextBuffer.prototype.move_mark, you will temporarily select a region in between their old and new locations, which can be pretty inefficient since the temporarily-selected region will force stuff to be recalculated. This function moves them as a unit, which can be optimized.