Watch out 1.0.x theme authors! You need to add some CSS for Mozilla 1.0.2. Without them, you cannot re-launch Mail/News, and in my case, Moz stays in background when I quit Moz after the failure of Mail/News re-launch. Solution is easy. Just add CSSs mentioned below in /messenger/.
- messageKeywords.css
- folderPaneExtras.css
- threadPaneExtras.css