itemState change events from UserInputPanel combos unconditionally cause revalidation; behavior should be controlled by REVALIDATE attribute instead

Every time the user selects a different item in a ComboBox on the UserInputPanel, the entire panel is revalidated. This is very distracting if one or more Validators are attached to fields on the same panel and they display their error dialogs one after the other
Instead use the REVALIDATE attribute for ComboBoxes in the same way as Check Boxes.
Patch attached.