Hi. Again I’m doing this feature request: https://www.steinberg.net/forums/viewtopic.php?f=252&t=131583
Thanks! 
+1
I am working mainly in the arrange window and barely use the mixer at all - as the most common functions for mixing are accesible via inspector or edit button on the track itself. iThe only time I am forced to open the mixer is, when I want to use the “add group channel to selected channels” - command.
Super annoying!!!
Please make it availible in the arrange window right click menue.
On the other hand I just created a key command for “add group channel to selected channels” and it seems to work in the arrange window without the mixer being opened.