RTFM!! or Read Blogger Help :-(

There's a compatibility matrix in Blogger Help for browsers...

Unfortunately, 'Safari', doesn't do a bunch of useful stuff. Like support the wysiwyg editor.

Firefox does. Fired up the version I had (1.5.6?), loaded the update (2.0.1).
Installed and running... With the wysiwyg editor :-)

Have to check whether the auto-install replaces the '.app' in Applications.