Thunderbird has been using a variant of the Australis theme (rounded tabs, menu button in the right) for over a year. Firefox for Android also has been shippin

Thunderbird has been using a variant of the Australis theme (rounded tabs, menu button in the right) for over a year. Firefox for Android also has been shipping with a similar theme for quite some time. So I suppose they've had ample opportunity to see how people react to it.