Is there a way to control how long a grid's cell length is? I'm trying to have an inventory system that displays how much of what you have, so I made the grid have 2 columns. I output the item in the first cell and the total in the second cell. I have looked in the skin reference and I have found no such parameter.

I suppose alternatively I could have a second grid handle all of that, but it couldn't hurt to find out if there is a way to control grid cell length.
I think one way would be to only use a single column and handle everything through HTML.
You can even color the cell, put a single image in it and a link, if you wanted.
(Basically, you'd have to put an <img> tag, several spaces and some text being sent to each cell. You could even put icons there that don't match world.icon_size.)

If you don't want hyperlinks (handling client.Topic, etc.), you could just get the cell from the client.Click to figure out what item was clicked.

Other than that, and what you mentioned, there isn't really a way to do it. (At least not in my knowledge.)
In response to Complex Robot
I'm not smart enough to handle all of the fun HTML and whatnot so I guess I will have to make do with the 2nd grid. Thank you for telling me this though.