Is there any pattern to which skills can go on the sidebar? I was thinking that the Survival-Utility skills were the ones that were allowed to be placed there, but not all of them can. Flesh to Fuel can be placed on the sidebar, but Look At My Hammer cannot.

I was not sure if this was intended or a bug. No one in game seemed to know, so I thought I would ask here.

Can anyone explain which skills are intended to be allowed to go on the sidebar? Is it just whichever ones the developers specifically designate? Or is there a pattern and Look At My Hammer got missed?