We modify the tab previews code in 4 places to make sure that the code is using gBrowser.visibleTabs instead of gBrowser.browsers. We need to have four tests which test the individual methods in presence of a hidden tab to make sure that the hidden tabs are skipped by the tab previews code.
I can only see 2 places which are using the gBrowser.visibleTabs in browser-tabPreview.js. May be other 2 have been removed. I will look into those 2 places.
Mass moving all Tab Candy bugs from Mozilla Labs to Firefox::Tab Candy. Filter the bugmail spam with "tabcandymassmove".