<robohelp 9> Insert link to go to the top of page

Hi all,

I intend to insert a link called "To the top" at some places in each topic. When users click to this link, they will be moved to the begining of the topic.

If i put this link to the master page then apply this master page to all topics. So there is any way to hide this link automatically if the topic content is short and doesn't need to use this link ?

Thanks in advance.