OS: Windows XP Pro SP 3
Kdiff3 0.9.93
When comparing directories and the text view is not open or the option "Dir & Text Split Screen View" is off (and only directories are shown), the shortcut works to set merge operation of a file to "do nothing".
If the text split screen is also visible, the shortcut doesn't work, other shortcuts (e.g. Ctrl-1 or Ctrl-Del) work.