I haven't been able to find a way to adjust column width.
Here's a bit of a dangerous bug: According to the Help section and the Keyboard shortcuts pop-up, tapping the "a" key while looking at the list of messages will select all visible messages. It seems to select all messages in the folder, even if they are not in view. Move to the next page of messages, and you'll see they are also highlighted! if you then tap the "d" key to delete them you will effectively empty the folder you were looking at, not just the pageful of messages you were looking at. Please note that I tested this with IE8 and Opera 12 (just in case it's a problem that affects particular browsers).
There have been times in the past, while helping clients upgrade to new computers, with new e-mail programs, where it would have been wonderful to delete several tens of thousands of messages that had accumulated in their online inbox, but even so, having the "a" key shortcut select all messages, both visible, and invisible, when it's only supposed to select the visible ones, is a bug that should be fixed.
I wouldn't mind keeping this power to select ALL the messages in a folder, visible or not, as long as it's a bit harder to do, so that it doesn't happen accidentally. I also wouldn't mind the on-screen alternative I requested in my post above, especially since most webmail systems offer an on-screen way to select all visible messages.