>sendHostMessage( )</a>. Only one message is processed for sendGUIUpdate that provides a mechanism to update the GUI controls from the plugin core. Note that this is not an ideal solution for most problems (e.g. linking controls together intelligently) &ndash; you should always consider using a custom sub-controller and/or custom view to do this properly. On occasion, a more difficult scenario may arise (e.g. MIDI learn button, that must wait for user input from a MIDI instrument to toggle states) where the