Sitemap item picker dialog width is not adjustable

When working in the HST Configuration Editor perspective in the cms you can work with the Site Menu's. When entering a URL Design reference, you can use the URL Design picker, which pops up in a dialog window.

When the sitemap items are for example 4 levels deep, and they have even medium long names (e.g. /first-level/second-level/third-extended-level/fourth-level), the tree does not fit in the dialog window. Of course you can use the horizontal scroll bar, but even then the overview of the tree is far from convenient.

Making this window resizable (or quite a bit bigger if that is impossible) would be a very nice improvement indeed.