The following diagram does not show the times at the bottom anymore. This is caused by adding scale to the diagram.
Maybe I am just using scale wrong with time?
@startuml
scale 100 as 100 pixels
robust "Web Browser" as WB
concise "Web User" as WU
@1:15:00
WU is Idle
WB is Idle
@1:16:30
WU is Waiting : some note
WB is Processing : some other note
@1:25:30
WB is Waiting
@enduml