I noticed that I can’t select leader dimensions via the '_SelDim. Instead, the Rhino documentation mentions that there is a toolbar called “Select dimensions” that includes an icon named “SelLeader”. However, I fail to figure out where that toolbar is located, nor I can find the said icon. Any suggestions where to find the “Select dimensions” toolbar? 
Possibly as a sub-flyout in the general Select toolbar? I’m not in front of my Rhino right now.
Hi,
I think it’s referring to the main Drafting toolbar.
Which is also in the main Selection toolbar.
However it’s said that SelLeader isn’t in toolbars, only in the Edit menu.
It’s quite strange that SelLeaders is kind of a hidden command and does not exist on toolbars, despite the fact that leaders are a typical dimension type used on many drawings. It would be nice to see SelLeaders as a default RMB command assigned to some existing icon.