Mac OS X offers a dashboard to store third-party widgets. This is not new to Yosemite, but in Mavericks you only had the option to show the Dashboard as a space or not. Yosemite brings back the option to show the dashboard as an overlay on your current space. Learn how to adjust your dashboard to display the way you want it.
1. Choose “Mission Control.” in the System Preferences menu.
2. Change the Dashboard drop-down menu to “Off” to disable the Dashboard completely.
3. Leave the Dashboard drop-down menu in “As Space” to open it in a separate space on the far left of all your spaces.
4. Change it to “As Overlay” to go back to the early OS X version of the Dashboard, where the widgets appear directly over the space you’re in.