Version: Kontact 1.2.4 (using KDE KDE 3.5.8) Installed from: Ubuntu Packages OS: Linux After editing Categories in order for this to be visible in Filters you have to quit Kontact and restart.
Confirmed in KDE 3.5.8 from Ubuntu packages.
This bug has only been reported for versions before 4.14, which have been unsupported for at least two years now. Can anyone tell if this bug still present? If noone confirms this bug for a Framework-based version of kontact (version 5.0 or later, as part of KDE Applications 15.08 or later), it gets closed in about three months.
Just as announced in my last comment, I close this bug. If you encounter it again in a recent version (at least 5.0 aka 15.08), please open a new one unless it already exists. Thank you for all your input.