Open two windows. Don't do a bunch of tabs, just the two windows. Leave them in the same desktop.

Have both open and not minimized so you can see changes in each.

Go to the menu bar at the top of the desktop and open a single bookmark. See if it opens in the NON-active window.

Do the same with a single history item. It'll open in the NON-active window.

Now Bookmarks/Show All Bookmarks will open in the active window as will History/Show All History

Oh, if you have bookmarks in a bookmarks bar inside the browser window, those will open in the current browser tab. Move things you use regularly to the bookmarks bar until they can find a fix for this or open a new tab, go to the other window and use the Bookmarks menu bar item to open bookmarks. Bit of a pain but you don't move off a page you want to keep inadvertently.