I run my MBA with an extra monitor (Asus PA238Q via DisplayPort). The MBA remains the primary screen, the Asus is just like a second monitor. My issue is with Clamshell mode. Whenever I close my MBA to put it to sleep it enters Clamshell mode. I don't even own an extra keyboard (BlueTooth or wired) and I almost never have my mouse plugged in. There is no need for the MBA to enter clamshell mode but it does it anyway. Is there a way that I can disable Clamshell mode? I don't think I'll ever use it and it is very annoying.