Normal people hate hierarchies. I've spent a lot of time trying to teach non-programmers to us them in their work flow. There is no question that they are usefu

Normal people hate hierarchies. I've spent a lot of time trying to teach non-programmers to us them in their work flow. There is no question that they are useful, but people resist them fiercely. Many developers have a hard time dealing with this and are as resistent to acknowledging this limitation, or feature, of human behavior as most people are to using said concepts. In a lot of ways this is understandable. You don't see many directly manipulate hierarchies in nature. People can deal with piles, and one or two dimensional arrays, and even arrays of piles. And they can deal with sorting and stashing. More importantly, they can deal with ask and tell. I've played with various stack based interfaces and while they are interesting, I haven't found any that I really like, much less that seem generally extensible. I dont have any great ideas here, sometimes I think the answer is to let the user dig holes in the desktop and bury what they aren't working on in little treasure caches; this essentially describes most users' desktops anyway. how you would go about generalizing this to, say, a CAD system interface is another question...