Prolonged display of HUD elements on certain CRT-based screens may cause permanent damage in the form of burning into the inner coating of the television sets, which is impossible to repair. Also players who pause their games for long hours without turning off their television or putting it on standby risk harming their TV sets. Plasma TV screens are also at risk, although the effects are usually not as permanent.
Burn-in can still happen on LCD monitors, but only when the same image is displayed for weeks.
In Mac OS X applications, heads-up displays (or HUDs) usually take the form of miniature, darkly-colored, transparent windows which are revealed outside the window of the currently-running application. Their purposes vary, from simply displaying information concerning a currently-running task, to displaying the tools for carrying out the task. HUDs often overlap with palettes, a similarly-functioning GUI element that usually fits the general interface of the main parent application (see Dashboard).
HUDs can also figure in larger settings, such as the display modes for the Exposé and Dashboard applications.
In recent years[when?], Mac applications have started to utilize HUDs as displays for buttons and controls, such as in QuickTime, which shows the user a transparent, rounded, and rectangular control bar that floats within the bottom of a video but does not touch the very bottom of the application window; this is usually the main means of control of the video playback when in full-screen mode.