This took me a while to figure out.
I tend to like to save my bookmarks in a txt file and open them in command line all at once .. but i like to read the current page while the rest are loading.
the default behaviour in flock is to switch immediately to the new tab which is distracting to say the least!
to change this
in the url box
and search for this preference name
click on this to set it to be true
Voila! fixed .
p.s. it look me a while to arrive at this after reading thru the mozilla knowledgebase and trial and error by comparing my firefox settings with my flock settings. I wished i had done this earlier!