As I mentioned, Gordita has a problem on Firefox 2.0. Here’s a workaround for Mac folks so you don’t have to leave the keyboard.
What you’d like is a key combo that’ll switch from the current Firefox window to the one that just opened behind it. Unlike the PC where all windows are created equal and alt-tab will cycle between them, on the Mac command-tab cycles between applications. If an application has multiple windows open, only the focus window can be switched to with command-tab.
Turns out you can use command-` — that’s command-backquote on OS X to cycle between windows of the current application. When your Gordita pops up the del.icio.us window behind the focus window, hit command-` and assuming you had no other Firefox windows open, it’ll cycle your little del.icio.us window to the top.