Event.functionKey
var functionKey: bool;
bool functionKey;
functionKey as bool
Description

Is the current keypress a function key? (Read Only)

Returns true if the current keypress is an arrow key, page up, page down, backspace, etc. key. If this key needs special processing in order to work in text editing, functionKey is on.
	// Detects if a function Key was pressed if a
	// function key was pressed, prints its key code.
	function OnGUI() {
		var e : Event = Event.current;
		if (e.functionKey){
			Debug.Log("Pressed: " + e.keyCode);
		}
	}
using UnityEngine;
using System.Collections;

public class Example : MonoBehaviour {
    void OnGUI() {
        Event e = Event.current;
        if (e.functionKey)
            Debug.Log("Pressed: " + e.keyCode);
        
    }
}
import UnityEngine
import System.Collections

public class Example(MonoBehaviour):

	def OnGUI() as void:
		e as Event = Event.current
		if e.functionKey:
			Debug.Log(('Pressed: ' + e.keyCode))