MonoBehaviour.OnGUI Manual     Reference     Scripting  
Scripting > Runtime Classes > MonoBehaviour

function OnGUI () : void


OnGUI is called for rendering and handling GUI events.

This means that your OnGUI implementation might be called several times per frame (one call per event). For more information on GUI events see the Event reference. If the MonoBehaviour's enabled property is set to false, OnGUI() will not be called.

function OnGUI () {
if (GUI.Button (Rect (10,10,150,100), "I am a button")) {
print ("You clicked the button!");

For more information, see the GUI Scripting Guide