Check that it's not on your external display. If you still can't find it: 1) Close MixEmergency 2) Open the Terminal application 3) Copy and paste the following text into the Terminal window defaults delete com.inklen.MixEmergency "NSWindow Frame OverlaysWindowBeta" 4) Press the enter/return key 5) Reopen MixEmergency You should now be able to hide and show the overlays window.