KDE 3.x and KDE 4.0 allow slashes in filenames by encoding them as %2F (and % as %%), a nice trick by Torben in KDE-1, but which leads to unexpected behavior (like "foo%" and "foo%%" both showing up as "foo%" in konqueror, the real path and the visible filename being different, etc).

I found a much better solution to allow '/' without all this escaping: using a unicode character that looks like a slash but that isn't '/': QChar(0x2044), also known as "FRACTION SLASH".

As discussed on kfm-devel.