Hope it's OK to jump in here for quick comment. I feel that one becomes accustomed to just about any visual change/flash/momentary icon color when you know it's going to or supposed to happen. For instance all that might be necessary for most users may be a change in the tray "clipboard" icon color, or a momentary indication on near the position of the copy/or paste.
Well, I'm beginning to see how difficult it is to "whittle" down a lot of bright ideas, so, thats my take and hope it can help for the future. Thanks for your attention.