After the unified back/forward buttons was landed, when customizing toolbars, the back button and forward buttons are the old icons and the back button gets a drop down arrow. This happens when the icons are set to 'Icons', 'Text' or 'Icons and Text' mode.

This comment https://bugzilla.mozilla.org/show_bug.cgi?id=414362#c3 makes me think the issue is that the attribute doesn't always reflect the state of currently selected icon size? I haven't seen it for myself yet but that's what it suggests.

Arrrg ignore comment 1. I was reponding to another of your bugs from this morning.

That's actually the expected behavior: Users still have the option to separate Back and Forward buttons, in which case they behave as for Firefox 2.0 (keyhole parts wouldn't really make sense). Or the other way round: you only get the keyhole when both buttons are adjacent - which they needn't be while you're customizing. -> INVALID?

(In reply to comment #3) -> INVALID? In my opinion yes. There are arguments either way (on one hand -- users may be searching the customize palette for the keyhole icons because that's what they want on their toolbar, not realizing the separate back and forward will turn into the keyhole version when they're put on the toolbar? -- on the other hand, what Simon said, in which case user want to see them separated), I'm thinking the current approach makes the most sense.