This extension allows the user to change the background color of the current page.
Opentime is an extension that allows you to quickly share your calendar with others, without sharing the events themselves. First, go to your calendar. Then click the Opentime extension button. All of your events will be blacked out. Now you can screenshot and share which times you are NOT free, and your friend can find a time within the gaps. Currently, to revert back to the normal calendar view, a page refresh is required.