I had already figured out how to set a hotkey to turn on auto-size columns (Set AUTOSIZECOLUMNS=focus), but it doesn't work in List view. (It only works in Details view, and maybe in Power mode as well.)
For general file browsing, I like to use List view because it allows me to see the greatest number of files on screen at once, in the most ordered format (in my opinion). What I don't like about it is that the column width must be set to the longest filename width, which may be much longer than is necessary for the rest of the columns. Win7 seems to have addressed this by allowing multiple different columns sizes accordingly, but another way I've addressed this issue in the past is by leaving auto-size on, and then manually shrinking (and expanding, if necessary) the columns when I want to see more files and don't care about some of the names getting cut off.
Therefore, it's handy to have a hotkey to shrink/grow columns. I was hoping to see a feature that supported that, as another file manager I've used has the feature, and DOpus is one of the few file managers that I've found that, so far, I've been impressed with the sheer amount of features and configurability.