[TxMt] file browser width in 2-alpha-9383

I prefer to keep narrow editing windows (mostly for LaTeX) especially on my portable machine. At the user's level, I've set WrapColumn = 67 and showWrapColumn = true. Up to and including r9377, I could still have a file browser window with flexible width.

With 2-alpha-9383, this admittedly narrow document window---with 67 characters + a few more to the right of the wrap column---is broadened by the file browser to something like 80 characters or so. When toggling the file browser, the window stays at that new width. I can see the file browser's width flexibility is all there when I have a broader window. I would like to get back this flexibility even with narrower windows. Possible? --Gildas