If a URL points to a resource whose content type is handled by an external application (not Mozilla or a plugin), then there is no way to request a refresh. For instance, if http://foo.com/news.doc has changed but is already cached, you cannot ask Mozilla to retrieve the current version. Even clearing the memory and disk cache may not help, since the old version may be cached in intermediate proxies and normal HTTP retrieval, unlike a refresh, does not issue a "Cache-Control: max-age=0" header. Some possible solutions: 1. Add an "Open Refreshed" item to the context menu of links. Its action would be similar to a click, except it would force a refresh. Note that this makes sense for HTML resources too. However, it does not help when you enter the URL manually rather than follow a link. 2. Make Alt-click have a similar effect. 3. Drag&drop a link onto the refresh button, or vice versa. (Highly nonstandard.) 4. Currently, when you attempt to open an externally handled resource, the external application is activated but the logical "current URL" of the Mozilla windows where you were working is unchanged. This makes sense when you follow a link, but in two other cases it's reasonable to change the behavior: when the URL is entered manually (e.g., using the URL bar) and when you use "Open in New Window" or "Open in New Tab". In these cases Mozilla can record the new URL, and then the Refresh button would refresh and reload the external resource. Alas, this would usually mean that you need to first load the old version and close it, and then load the new version. BuildID: 2002020406
Actually, the same problem is with content that will be saved to disk, i.e. when no application is associated with the MIME type. I agree with the "Open refreshed" hyperlink context menu option, and perhaps also "Save refreshed link as", but then the menu is getting too long, I guess. For pages that you open by typing into the location field, Shift+Enter (in analogy with Shift+Reload mouse click) could do the trick, and Shift+click/enter on bookmarks. There is one more situation where this does not help: when you submit a POST-form and the result is something that you want saved to the disk, refreshed. For that, a "Submit and reload" ("submit refreshed" doesn't seem to make sense) menu option should be in the context menu on submit buttons. I have been missing this possibility very much. Actually, the said form could be submitted programatically, triggered by a completely different action, and then I'm really short on ideas how to force a reload of the result.
To file handling. This would be nice... can't think of how to do it, though.
*** Bug 209627 has been marked as a duplicate of this bug. ***
An interesting solution would be to present an intermediate page representing that link. That would solve some other problems, too, such as the difficulty of bookmarking an externally viewed document and the odd effect of opening a PDF file in a new tab. For example, when I click on a PDF link I would see in the browser a page which says "Now downloading myfile.pdf" with the PDF's URL in the URLbar, and the download would initiate and the viewer launch. I could then use all of Mozilla's normal interfaces for working with that page---refresh or shift-refresh to request that the document be requested fresh, bookmarks for saving the URL, Send Page to email the document to somebody, Page Info to see content-type and other information, etc. Another place for this interface could be in the Download Manager.
Note bug 288462.