It is a few years than I was not using debian and I am very badly surprized to constat than Xdialog is not in squeeze. I think this is a shame because it work and many peoples can have, like me, shell scripts that depend on it. I am not a programmer, but I can make shell scripts, and Xdialog is a very simple and efficent way to make interactive shell scripts for X.
I have no time to arge on it, and no interest beside those raisons, but I think that it would be a good move to make a squeeze gtk2 build of Xdialog.
I have no problem to install it on opensuze (a search and a few clicks) and gentoo (emerge xdialog). I just installed it in squeeze, and it seam to work very well. To get it to work with gtk2, it is just to configure it with "--enable-gtk2" and all is going fine afterwards.