Take screenshot of onscreen element from Safari quickly and easily.
Enable this extension from Safari.
1. Control-click (right-click) on the HTML element on Safari. 
2. Choose "Capture Selected Element". 
The screenshots are saved in your “Downloads” folder
                                
Clip It! for Safari V1.1.0更新日志:
                In the menu item, you can choose to disable/enable Clip It!. When you don't need to take screenshot, the detection highlight won't appear anymore!