Wrong menu entry in KDE, needs gksu

Is there a programmatic way to determine (at install time) if the user is running gnome or kde?

You could have a wrapper around gksu or kdesu running one or the other depending on the current session; such a wrapper is provided in the menu package, but you don't want to pull that, it changes gnome menus.

The "update-manager" utility which is used in both KDE and GNOME in Ubuntu calls gksu; this is what I'd recommend for now with a dep on gksu.

There should really be some simple wrapper to remove this issue!

#!/bin/sh

if [ -x /usr/bin/gksu ]; then
  /usr/bin/gksu $@
elif [ -x /usr/bin/kdesu ]; then
  /usr/bin/kdesu $@
else
  echo "What the h...?" >&2
fi

I wouldn't recommend the above wrapper, but instead checking for session env vars. The proposed wrapper only checks what's on the system, and doesn't take into account which DE the user runs as.

sensible-browser checks whether the GNOME_DESKTOP_SESSION_ID env var is set and launches gnome-www-browser in this case. I think KDE sessions probably expose a similar env var which could be used in heuristics.

As update-manager is already using gksu in KDE sessions, I don't see much point in being too creative for this particular app. I'd rather recommend starting a wider discussion on this topic, perhaps we could come up with sensible-su-to-root or something.

(The current trend is to move programs to PolicyKit though.)

To detect a KDE session, you can use KDE_FULL_SESSION. This said, you
may still want to use kdesu in Gnome or gksu in KDE sessions when
that's the only thing you've got... I suppose XFCE uses gksu too, so
that should be the default. So:

if kdesu and (KDE or ! gksu)
  kdesu
else
  use gksu

yes, agree, this might be a correct solution.