AFAIK there is no built-in phase shift calculation formula in PS6. To measure phase between two signals one either uses cursors or this formula that has been circulating on forum for a while:

(acos(integral(A*B)/(sqrt(integral(A*A))*sqrt(integral(B*B))))/Pi*180)

Who has used given formula probably noticed it has some shortcomings, especially with small numbers of wfms on screen. For my work with "virtual MSO" had to come up with means to somehow make analog signal discrete using only trigonometry. This gave idea for completely different approach to phase shift calculation, which worked quite well - accuracy to acquisition natural limit and no "settle time":

((((atan(1/tan(pi*(A/10000)))/pi)+(A/10000))*-((atan(1/tan(pi*(B/10000)))/pi)+(B/10000)))+0.25)/0.002777777

Input: 40°

newPhase(A;B): 39.86°

Cursors: 37.54°

oldPhase(A;B): 55.84°

Since this work is quite new cannot fully exclude there's room for further improvements. Suggestions are welcome.