Minor Description
When the palette component loads, both selection arrows (select/deselect) show the enabled images, even though they should be disabled as no items are highlighted on load. You can see the javascript defaulting them to disabled:
<componentId>$buttons.selectDisabled = true;
<componentId>$buttons.deselectDisabled = true;
But the javascript function update_<componentId>() isn't being called, where the switching of the enabled/disabled images happens.
For a workaround i've added a call to the update javascript function on page load. But this is semi-fragile as if the component id is changed the generated function name will also change.