When you begin a Custom Display session, a temporary in-place edit profile is drawn around the object being edited, and all other objects in the drawing are unavailable and dimmed.
Note: You can change the brightness of the dimming that appears during a Custom Display mode session. Click 
Options Display tab. Under Fade Control, for In-place edit and annotative representations, enter a value or drag the slider, then click OK.
Options Display tab. Under Fade Control, for In-place edit and annotative representations, enter a value or drag the slider, then click OK. After making changes, you can save the changes and exit the Custom Display session. Alternatively, you can discard the changes before exiting to revert to the original state of the object.