Browse plugin presets with the keyboard

Hello,

In a plugin window (say Amsynth) When using the “presets” menu button, after selecting a preset/patch I can’t seem to use the keyboard’s arrow keys to select another one, is there a way to do this, listen to presets without resorting to the mouse?

If not, would those “preset” concepts be exposed to LUA scripting (http://manual.ardour.org/lua-scripting/) allowing me to code something like “Track:First_plugin:select_preset(current_preset+1)”?

I would appreciate an answer to this question too.