MSIE always allowed this as it had an Open in Editor icon ie Frontpage or whatever you set up in options.
BUT I have been finding Ie7 unstable and wanted to use Firefox.
But I could not see a way to open my files in Frontpage.
Anyhow I just found an add on JSVIEW
the options include pick your own editor. So now I just right click on the page when in Firefox
select Jsview and up comes FP.
Also CSS support and other features which I have yet to explore