Indicate which layers are time aware and only have the Time Slider active when time aware layers are on

I think it would be really helpful if there was some sort of indicator for which layers are time aware, maybe something like a little clock by the layer name that has a tool tip when you hover over it that says something like "This layer is compatible with the time slider". 
Additionally, it would be nice if the time slider is deactivated when there are no time-aware layers on.  I am planning on using the time slider in a map with several different layers, and only a couple of them would be time aware.  If the user is not interested in these layers, I think it would be confusing for them to be able to turn the time slider on and mess with the settings when it doesn't affect anything currently visible in the map.