I'm working on an app which supports live editing. That is you update properties in one area and their impact is seen in another with hitting "apply". Happens to be a charting app. One such edit "group" allows specifying a range. A triple range in fact: High, Target and Low.

Our validation is such that High must be greater than target, target must be greater than Low (rocket science).

Our dilemma is that the visual experience is a bit jarring when someone wants to go from say 30,20,10 to 15,10,5. I'm curious if anyone has implemented a mechanism for this scenario that might fit well in our situation such that we don't "yell" at the user as they change the range values.