> According to the Emacs 22 News it is a policy decision that space > no longer > causes completion but instead appends a space to the filename, thereby > making it much easier to enter filenames containing spaces. I think this > change is a good idea. Tab still completes, so you just have to > relearn to > hit tab instead of space.
Eli has mentioned how you can turn off this new feature, if you wish. FWIW, here is my story about this feature - I was very used to using the space bar for completion - very handy, especially because of its large size. However, based on this change, I made myself try to get to used to using TAB. I did that because 1) spaces are more and more common in completion candidates and 2) word completion (what SPC used to do) is not that useful anyway. I even changed the Icicles code to allow SPC to act as an ordinary character - not only for file names but in general (Icicles allows for other kinds of completion candidates, many of which naturally contain spaces). A different, customizable key sequence (Meta-SPC, by default) is used in Icicles for word completion. IMO, this Emacs 22 change is a good idea, but I recognize that it can be a PITA to get used to the change. After decades of the habit of hitting the space bar, it took me at least a couple of weeks to adapt to using TAB. But I'm glad I did. Word completion is not all that useful, anyway, in most contexts, and I think using SPC for completion was mainly the result of the convenience of hitting the space bar. Now that I'm used to the new approach, I don't miss the old one at all. HTH. YMMV.
