Occurs when any worksheet is double-clicked, before the default double-click action.

在按两下任何工作表时 （在预设的按两下动作前） 发生。

youdao

It's a little puzzle piece that says when the green flag is clicked and this is kind ; of like the beginning of a program; when you double click an icon on your desktop this is how something like that is implemented; it's listening for that double click, it's listening for that green flag.

是一小个按钮，它的意思是,何时点击绿色旗帜,这就好比开始运行程序;,当你双击桌面上的图标,就开始执行操作,桌面的图标需要双击，绿色小旗也等待点击来执行命令。

哈佛公开课 - 计算机科学课程节选

Double click start button, you get a button that when clicked will let you take a photo.

FORBES: Apple: Live From The WWDC; OSX Lion, iOS 5; iCloud