DO11: How to turn off the toolbar in thumbnails mode?

Really need space in thumbnails mode, so I set Preferences / File Display Modes / Toolbars / Thumbnails = None, it works, but when I restart Opus, the Image toolbar appears again in thumbnails mode. Is there a way to turn off the toolbar in thumbnails mode?

Thanks, guys!
I'm using Diretory Opus 11 beta 2 x86 on Windows XP SP3.

It's a bug: automatic tool bar keeps coming back
Setting this option to another Toolbar works. So you can choose a toolbar which is always present for you as a workaround. Only choosing "None" seems to be broken and resets the Image toolbar.