Is VST on/off or FX enabled/disabled?

In Reaper, VSTs can be toggled, by setting FX enabled or disabled. Is there a way to notice that action in the JUCE VST? I would like to interrupt my VST’s OSC sending, when the FX is disabled in Reaper…

I have always been under the impression that when a VST is disabled, its processBlock() simply does not get called.