I'm using 2.5.8 and 2.6.0 Beta 2 (first betas, with old skin) daily and i have never seen such behavior. But with the latest SVN version when Bring window to front is not enabled and Show toast popup is enabled. If you type in some other window and new messages arrives, then your current window loses focus. This happens only if toast popups are enabled. When not enabled, then new message just flashes in the taskbar and focus is not lost.