So I just tried to scroll a staff with Legendary spirt and ended up accidentally using a white scroll. It seems by default the white scroll box marks itself automatically when there is a white scroll in the inventory, and unmarks when there isn't one. I think it would be for the best if the box doesnt mark itself automatically since if it is marked, it will not ask you whether or not you want to use a white scroll
I believe that is a client limitation and not something we have control over but I will defer to others who have a bit more knowledge on this.
1. Create a lvl 7 nib mule who can't scroll anything useful and have the Legendary Spirit skill 2. Put all your WS there 3. ??? 4. Profit