Comment # 8 on bug 979265 from Enno Nagel

Ok, true

krusader -caption "%c" 

opens Krusader. To take stock, there's a file

/usr/share/applications/kde4/krusader.desktop

with

Exec=krusader -caption "%c" %i

and a file

~/.config/mimeapps.list

that, as soon as 

inode/directory=kde4-krusader.desktop

then xdg-open . does not open Krusader anymore, but Dolphin, probably due to

inode/directory=org.kde.dolphinsu.desktop

in a file

/usr/share/applications/defaults.list

Now a hint:

as soon as in 

/usr/share/applications/kde4/krusader.desktop

the line 

Exec=krusader -caption "%c" %i

is replaced by

Exec=krusader

then 

xdg-open .

does start Krusader. 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.