How can I map a click in Vim?

I want to be able to click (or cmd+click on my Mac) on a function name in Gvim (or vim with set mouse=a) and have it run the command :tag to follow a ctag, but I don't know how to include a mouse click in a Vim mapping.

From stackoverflow Drew Stephens

• A good place to start:

  :help click
  :help mouse
  

  Perhaps something like this will work:

  :map <RightMouse> :tag <CR>
  

  From Marcin