[HaoleKai]

Kovid and user_none,

Ok, there are a few things going on here. First, when I posted my comment, I'd already re-installed 7.54 so was writing from memory of 7.55 and making some assumptions. I should have included screenshots, but I was assuming others saw the interface the same way I did. I'm now running both so I can do screenshots and compare issues.

It is not 2.5x taller, but it is more than 5 pixels larger as can be seen in my screenshot.
The difference is significantly greater when switching to small icons since the icon bar itself doesn't resize - see screenshot. Yes, I've restarted the app and tried changing other settings, but the bar doesn't resize.

It's also not that there's extra space between the icons - they're all shifted to the right due to the extra gutter space, but when I loaded 7.55, the Help and Preferences icons were gone. When I reinstalled 7.54, they were back. I made the assumption without looking into it that they'd been 'pushed off' the screen. See screenshot. In fact, they're just dropped from the 7.55 interface, and I can put them back.

I didn't even notice until now while comparing screenshots that you have added the Mac menu bar!! Thank you, that's what's been missing this whole time, and I can probably get rid of and get used to using this app without the icons anyway. One issue I did notice though is that the Preferences menu item doesn't actually allow you to load the preferences dialog box. For that, you have to go to Calibre/Preferences. That's confusing.

When I made the 'unusable' comment, it was more in reference to dialog boxes (such as the preferences and the icon toolbar windows) also getting bigger, and outsizing my screen so the buttons on the bottom are inaccessible. See screenshots. I realize now that if I hide the icon bar, then pull up those windows they fit the screen and I can also resize them so they'll fit later if I show the icon bar again.