当前热控件的 controlID。
The hot control is one that is temporarily active. When the user mousedown's on a button, it becomes hot.
No other controls are allowed to respond to mouse events while some other control is hot.
once the user mouseup's, the control sets hotControl to 0 in order to indicate that other controls can now respond to user input.
using UnityEngine;
using System.Collections;
public class ExampleClass : MonoBehaviour {
void OnGUI() {
GUILayout.Button("Press Me!");
Debug.Log("id: " + GUIUtility.hotControl);
}
}