Just FYI: I think I solved this by adjusting the column
widths dynamically via Actionscript. There was something odd about
how the grid handled the widths, though. I had to move the column
all the way to the right in the grid and then set it's width to a
negative value to "hide" it, which actually just pushed it off the
screen.
Let me know if you're still having trouble and I can dig up
the code, but it probably won't be that useful if you have to hide
multiple columns.