If you try and file your company reports from a Macintosh using any of Chrome, Safari or Firefox, you will encounter the following when you try to log in having saved-and-resumed a session:
WebFiling has logged you out as the browser ‘Back Button’ was used or a button was clicked twice. Please re-enter your login details below to return to WebFiling.
Fortunately it was Google FTW:
My solution was to use Opera – the “other” free Mac browser [www.opera.com]. I tested it on the only Annual Return that I have “current” at the moment. That is to say, I started under Safari, then crashed myself out, then went back in and got thrown out in the usual way. So I went back in using Opera and it worked fine … but it is only a single instance and not statistically significant. We need some more evidence that it works!
Opera (non-WebKit?) worked fine, so my reports are in; but sheesh, in this day and age? …

Incidentally, once CH get around to reading this:
1) There is no Internet Explorer for Macintosh any more, there has not been for several years.
2) I don’t really want to download and use Opera just for this one task.
3) My reports/filing was prepared by my accountant, so I had to log in, check, and submit them, and was not in a position to “Delete Everything And Start Over” else I would get billed more _by_ said accountant.
4) I would like this fixed, rather than have a workaround.