By accessing the Modular Keyer and the Colour Corrector directly from Action, you can key any media or colour correct any front, matte, or back clip without having to exit Action.
When you enter the Colour Corrector or Modular Keyer from Action, you can view the result of your colour correction or key as it would appear in Action by selecting Context from the View box. The Context view is interactive; as you make changes, the Action result is updated in the image window.
Use Result view while keying or colour correcting. In this way, the number of Action media has no impact on system performance. You can tweak the keying and colour correction setup using Context view.
While you work in the Colour Corrector or Modular Keyer, you do not have to click Render; the modifications are automatically applied to the media in Action. If you enter the Colour Corrector from Action, scrub the timebar to view the Result.
To access other tools from Action:
(a) Modular Keyer (b) Colour Corrector
You can mute Keyer and Colour Corrector media effects in the Action Media menu. Muting effect media can be helpful when you want to see what your Action setup looks like without the Keyer or Colour Corrector settings, but not lose any of the settings of the muted media effect.
To mute an effect, press Alt and click the K or CC media. The check mark in the field turns black to signify the media effect is muted. To unmute the media effect, press Alt and click the field again.

(a) Active media effect (b) Muted media effect