Zarqon -- of course $('#showall').checked wouldn't work, since the $() function returns an array of elements that fit the criteria, even if there's only one (in the case of matching for ID). I don't see how expand already exists, considering that you haven't defined it up to this point. Perhaps it's something unique to Opera's JS engine? Also, the issue with names is that I want to say that only works if they're inside a form, and ID works just as well in those cases (not for the wrapper form, just those). Or if it's an image (only name will work here, though, ). There should be some jQuery equivalent for grabbing the checked attribute, but the closest I can think of is $('#showall').attr('checked'), which is slightly more code than $('#showall')[0].checked.
Also, regarding my fix: It didn't break Opera (tested that, just for you and Bale), and it makes all the other browsers work. Which is generally good.
Edit: Just booted up Opera, and evidently anything with an id OR name is available as a variable in JS. What the heck? Looks like window.showall (which Opera abbreviates to showall) is valid in Chrome and IE8, at least, but doesn't seem to work with FF 3.6. That's actually kinda funny, that something works in IE but not in FF. Safari's console is apparently a pain to add for Windows, so I'll get back to you regarding Safari.
(further note regarding Opera: showall==expand returns true)
Double edit: Never mind about FF, showall (the id) is valid in everything (FF, Chrome, Safari, IE8, Opera). Try that instead of expand.
Triple edit: Also, an alternative to expanding the horizontal bar at the top would be modifying the CSS so that it looks like Opera regardless of browser.