1 File => Create Document => Empty File
2 Enter the file name "%S" or "%s"
3 click "Create" button
The Thunar window disappear quietly. copying files seams have same problem too.
I am using Gentoo amd64, just emerged xfce 4.8 from portage. my file system is ext4 and LANG=en_US.UTF-8
Fixed in master and the xfce-4.8 branch:
Author: Jannis Pohlmann <email@example.com>
Date: Mon Jan 24 20:06:35 2011 +0100
Don't interpret file display names as format strings (bug #7128).
This avoids a segmentation fault when creating files like '%s' or '%S'
using File => Create Document => Empty File.
BTW, this fix should also fix the same issue with copying.