Alt+TAB and the Emulator
I have heard this from many people. "I have the emulator running along with Multiple other application. I do (left)ALT+TAB to cycle between them. Once The Emulator gets the focus and then ALT+TAB does not seem to work."
No that is not a bug.
It's the way the Host Key is set of the Emulator.
To work around this option just go to File->Configure... on the Emulator, and then on the General Tab on the Emulator Properties just change the Host Key to Left ALT.
That way you can continue to cycles between apps without any issues.
On a related note, this is also the reason why when you typically would do (left) ALT+Prt Scr to take a screen shot of the emulator and nothing gets caputured. You can take a screen shot with the (rigth)ALT+PrtScr combination or change the host key to Left ALT.