Positive feedback needed when Apply is clicked in the Staff/Part Properties

When I enter the Staff/Part Properties dialog and make changes, the Apply button must be clicked before moving on the the next staff. If the Apply button is not clicked the changes are lost. However, there is no feedback that the button was actually clicked and the action taken.

I would suggest graying out the Apply button unless changes are pending. After clicking the Apply button it should then be grayed out again, confirming that the action was taken.