Users can interact more with the application, in such modes as drag and drop, or highlighting. To avoid false selections, the buttons have to be overly large. Light pens, in addition to a cursor, give the user acknowledgement from separate switch mechanisms, such as keyboard keys, or the nosetip or side switch on the pen itself. Touching the screen leaves a smudge. The screen has to be cleaned often in order not to present a dirty appearance.
Some touch screens use an overlay that can affect the quality of the image.
Results from touch screen polling applications may be tainted by smudges that leave a trail of previous selections. Light pens can be moved easily from system to system by the user, while touch screens require more complex set-up procedures. Some touch screen systems can only be installed at the factory. This also has negative repair implications. Touch screen repairs mean the whole system is down until the unit is returned and reinstalled.