If i want to see the left side , what should i do?

 From:  tyglik
215.14 In reply to 215.6 
>>So Petr, do you think that little menu was ok?

Since there is no need for me to change the reversed view frequently, it was.
But second click on the button to switch it, there is no problem at all. Furthermore, the Reset/ResetAll buttons use the same idea. You need to press it twice to see everything instead of only zooming to the selected objects. So it will be consistent and cryptic as well. Important is that you eliminated such options as RightView=rightMouseButtonClick, LeftView=leftMouseButtonClick.

However, I have doubt about triangle as Pilou has suggested. The small triangle in the corner of the button is a synonymous with "click and hold until the flyout toolbar appears". See AshlarVelum, Rhino and so forth. It might be more or less confusing.