Visually disabling parts of a device

Hi everyone,

I've been playing around with Max for Live for a couple of days now and already I'm kinda hooked on it ;)
I've always been a hands-on guy, I learn a lot from just looking how other devices are built. The built-in reference manual comes in handy too.
But for some things, I find it difficult to find an answer.

For example : How do I make controls in a device "grey"? Like in Beat Repeat, when the filter is off, the controls for the filter turn grey. I presume they are not deactivated, they can still be manipulated, their color is just greyed while the filter is in bypass mode. So I'm thinking it's just a visual thing, not really connected to the functionality of the controls.

So, any hints on how to achieve this are welcome.
Also, any suggestions on how I can look up these kind of things are also more than welcome. I can't really do a search on the example above in the reference manual.
Video tutorials are also great, but they're not searchable for keywords neither.
Is there any way to do this, part from looking for hours through posts on this forum?

Thanks,

Seth