http://bugs.winehq.org/show_bug.cgi?id=12464
--- Comment #17 from Andrea Denzler andrea@andreaplanet.com 2012-06-01 10:12:33 CDT --- I think the first question is 1) Do we want Wine to be an independent OS within the Host environment? or 2) Do we want the best possible integration between Wine and the Host environment?
Both approaches can be correct, it's a question of philosophy. Actually I think Wine developers prefer path 1). Under that viewpoint this here is not a bug, since there is no default PDF association (unless you install a PDF viewer within Wine). It is correct that Shell Execute does nothing.
The first approach is useful for replicating Windows applications under a Linux Host. I want a Windows PDF viewer, a Windows Browser, a (horrible) Windows File Manager.
The second approach is IMHO more useful for the End-User who wants to run some Windows programs under his preferred OS, probably because there are no available alternatives. Under this viewpoint ShellExecute should search for a Host file association (run xdg-open) unless a different file association is defined under Wine.
For my personal needs I just added a lot of registry entries (within the wine environment) all pointing to xdg-open, so for example the Host PDF Viewer / File Manager is actually used. But this is a viable solution only when the application and wine settings/configuration files are distributed within a independent container. This is not the default case under Linux where you usually have just one wine configuration.