Thats's a free tool there doesn't seem to be many of for linux. But hang on, lets look at how you use work on a linux box and how you work on windows.
The idea of having a desktop pager means that it's very easy to switch views between the runtime view and the code view. WYSIWYG editors are really a screen real estate optimisation, in other words you can graphically manipulate stuff and generate HTML from it right? Like Dreamweaver?
Well if you really want this (the analogy with FrontPage is like comparing VB to Java or Access to PostgreSQL) then try Netscape Navigator's composer. If you're looking to spend money for a WYSIWYG Editor, well you can always petition Macromedia
for the linux version of Dreamweaver.