You know, i don't like my idea so much that i have to keep pushing it, it just kind of annoys me i can't seem to make it well understood. So here it is again, for the last time (i promise!): when cpu usage goes above, say, 90%, the screen becomes black and white. There is no light fading (maybe even making it 5% brighter to compensate for lack of colors). There is no overlay and nothing to keep you from trying to interact with it, it just carries on as usual, but looks a bit different to let you know it's busy
Some apps are right to use lots of resources. When i decompress a .zip, i prefer a 10 second inactivity period and then back to idle rather than 2 minutes using 10% CPU. Apps should not be killed just because of resource use, and deciding which ones are not responding and which simply have high demands is hard