Comment # 10 on bug 979265 from Wolfgang Bauer

(In reply to Enno Nagel from comment #8)
> Ok, true
> 
> krusader -caption "%c" 
> 
> opens Krusader.

Ok, I hope you are convinced now that the "-caption" option is *not* specific
to a KDE desktop session and therefore the option per se is not the problem.

> But with either
> 
> Exec=krusader -caption "%c"
> 
> or
> 
> Exec=krusader %i
> 
> in /usr/share/applications/kde4/krusader.desktop
> 
> then again, Krusader fails to start under Awesome WM.

And a third time: do you get an error message?

If Exec=krusader %i fails as well, then probably the %i is the reason (although
as mentioned in comment#1, this is specified in the freedesktop.org specs and
is not at all specific to KDE either).
Does it work if the file just says:
Exec=krusader -caption %c
?