Browser with WYSIWYG editing abilities?

Hey everyone,

I edit a site at work using a WYSIWYG editing box in the browser. Problem is any time I want to update the site I need to stop what im doing and go find a windows Machine (we work on all Macs mainly!).

On the Mac (even in Chrome, Firefox AND Safari) I get the following box:



Does anyone know of a browser that works? The latest internet explorer is fine for it on Windows but nothing on the Mac will work even when I've installed firefox extensions.