I work in design mode and a lot of times want to use temporary attributes for storing partial calculations. This keeps the design blocks from becoming really large and difficult to manipulate.
The problem is that the temporary attributes take up space in the attribute tab and the "getter/setter" panels. This clutters up those panels with temporary variables that are only used in a single event.
My feature request is for attributes that only exist in the scope of a specific event. Ideally this would be implemented with a "local attribute" tab which duplicates the event-wide attribute tab in the design palette. Then in the getter/setter sections the attributes could be separated by event-local and behavior-global.
A step in the right direction that would probably be easier to implement is to have each event automatically initialize a single fixed name temporary attribute of each type, TempNumber, TempList, TempText and allow those to be used in design blocks without having to add them to the attribute tab.