So after all the trouble my idea from the last post gave me, after seeing how Firefox could not really handle different menu/nav/status bar settings for different windows, because new windows would always get it wrong, I thought why can't we just get rid of that menu bar for all windows. Internet Explorer and Google Chrome don't have a menu bar either! Now, how other browsers look is clearly not an argument for me to change my browser, but I know that a lot of other people like to copy things and so I thought: "There must be a Firefox Add-on that gives Firefox a Google-Chrome-like skin." I've used any skins myself, but I know it's a big thing and if it can help me, let's look for it! And indeed! Even on the first page of recommended Firefox Add-Ons I found one that's named "Personal Menu" and it's prime feature is "to disable the menu bar". I installed it and it's great! It offers a few extra buttons for the nav bar (like a bookmarks and a history button) plus one button that can be entirely customized to contain just those few menu items that one personally needs.
Here's how my Firefox looks like now:
For comparison, on Windows my Firefox still looks as before:
Now, I saved one line of screen real estate and I like it! On many pages I still need to do F11 (full screen) to read them well, but I think the browser has become better with much effort. That's good!