Open the Toolbar Customize mode and drag the Bookmarks button into the palette. https://support.mozilla.com/en-US/kb/How+to+customize+the+toolbar

"Forcefully present" is, unfortunately, supposed to mean that it cannot be dragged off. That's why I made this thread. In fact, I can't even move it. I can move other buttons to the other side of it to change it's location, but I can't move the button itself and remove it.

The button automatically goes away when I show the Bookmarks Bar, but I don't want to show the Bookmarks bar, because I don't want bookmarks at all.

You didn't state your problem too well yesterday, and I didn't test it as completely as I did just now. You are correct that it can't be dragged, but I wonder why there is a Bookmarks button in the palette already? That's what confused me yesterday, plus I didn't have the Menu bar hidden when I checked that out and didn't even see that other button on the Navigation bar. I don't use the Bookmarks Toolbar either, so I assumed the button in the palette was the only "Bookmarks" button for the Toolbars area. (Talking to myself a bit.)

That's not a function of hiding the Bookmarks Toolbar alone. That button appears on the Navigation toolbar when the Bookmarks Toolbar is hidden and then the Menu bar is hidden. When the Bookmarks Toolbar is not hidden, and the Menu bar is hidden, that button appears on the Bookmarks Toolbar - it is tied to the state of the Menu bar.

Use the Feedback button to report that issue, (unless you hid that button, too), so the developers are aware of that issue and they can (hopefully - 'cause that's going to bother me too) provide a preference to allow the user to hide that button when the Menu bar is hidden. I looked in about:config using both "menu" and "bookmark" as a filter and didn't see a hidden pref that looked like a pref for hiding that button when the Menu bar is hidden, along with the Bookmarks Toolbar.

Later this evening, when I have more time, I am going to search Bugzilla to see if there is a Bug filed about that button and the way it works, and if not already filed, I'm gonna file a Bug about it. I didn't realize it until now, but that's going to drive me crazy. I use the Bookmarks Sidebar exclusively (for 8 years now with Firefox) and I always hide the Menu bar (6 years with the Tiny / Compact Menu extension) and rarely, if ever, use the Bookmarks drop-down menu. I am also going to contact the author of the Tiny Menu extension and see if he plans an update, or a new version for Firefox 4 - that problem can probably be fixed in that manner, too. Overall, I am not impressed with the limited number of menu items available from the "Firefox" button when the Menu bar is hidden, and I would like that drop-down to show all the main menu items when the Alt key is used, not to just show the Menu bar itself - moving the entire window down when hitting the Alt key, instead of opening the drop-down, is going top make me dizzy real fast. (Yeah, I'm a bit "sensitive" to that shifting of everything down suddenly.)

Add code to userChrome.css below the @namespace line.

See http://kb.mozillazine.org/Editing_configuration#How_to_edit_configuration_files

@namespace url("http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul"); /* only needed once */

#bookmarks-menu-button {
 display:none!important;
}