Some users have noticed that the resolution on external monitors appears lower than that of the local MacBook monitor. The menu bar on an external monitor display appears less transparent than the same menu bar on the local display.
Reduce Transparency ON
Reduce Transparency OFF
Most likely the application is using a hardware accelerated effect that the software renderer in OSX does not support. To overcome this issue check box the “Reduce Transparency” option in System Preferences/Accessibility/Display.