Right click for online puzzles works normally in IE but not FFox

Hi all,

My kids and I like playing some online puzzle games but we've found that if we try to play them in Firefox, every time we use the right mouse button to mark in the puzzle, we get the context menu. As you can imagine, this is very frustrating. Is there a setting in FF that we need to change?

This is one of the pages: http://www.puzzle-nurikabe.com/

Every puzzle that is shown underneath with it's picture does exactly the same.

Thanks!

 

I forgot to mention - we don't have the problem with the context menu popping up if we drag when we're using the right mouse button. The menu only pops up when we mark a square with the right button.

Hope someone can help. :wave