Varia rtl510 I'd like an "always on " mode

the radar functionality is absolutely fantastic, that's why I always turned it on. 

But when riding in the city i would like to switch the tail light to stay "permanently on", so no flashing even when a vehicle approaches.

i could not find anything in the manual on this issue - I cycled through all modes but the Varia always switches from "on-mode" to "blinking-mode" when a car approaches from the rear.

i would appreciate any suggestions