I have a WebDav folder ("Web Disk") set up via CPanel and mapped to a Windows XP boxes and Windows Vista boxes.
On the Windows XP boxes, none of the files in the WebDav folder can be opened by double-clicking and there is no Open right-click option. The users can copy the files out to a local folder or browse from within an application.
On the Windows Vista box, the files can be opened through file-type associations, but still not by double-clicking–the users must right-click on the directories and select "Open". Even at that, only certain applications appear to be "WebDav-aware". For example, Adobe Reader will not open files from a WebDav location via file-type association (only by browsing from within the application).
Is there some fundamental issue with the WebDav configuration or is this the best one can hope for?
Best Answer
There are two clients in Windows for using Webdav. One is so called Mini-Redirector, other one is Webfolders.
You're using Webfolders client, which allows you browsing via shares. When you try to open any file, this client actually passes URL of the file to the program. Most program cannot handle that. MS OFfice programs can (presumably only if MS-Author-Via header is present, as Dave suggests in his answer).
Mini-redirector is used when you map Webdav share as an extra drive in your Windows (using NET MAP command, or by using "Map Network Drive"). In this case, Mini-redirector will handle loading/saving part of filesystem access, and your programs will be able to work with Webdav.
See also http://en.wikipedia.org/wiki/WebDAV#Microsoft_Windows for more details and links.
(Hint: forget about Windows webdav capabilities, and use better clients like Webdrive or Xythos).