Bind horizontal scrollbar to camera control

I am trying to make it so that the user has to be moving the scrollbar right and left in order to rotate the camera. This is the script that I have:

 using UnityEngine;
 using System.Collections;
  
 [AddComponentMenu("Camera-Control/Mouse Orbit with zoom")]
 public class OrbitCamWithXOffset: MonoBehaviour
 {
     public Transform target;
     public float zoomMultiplier = 1.2f;
     public float distance = 0.0f;
     public float xSpeed = 45.0f;
     public float ySpeed = 45.0f;
     public float rotLeftMax = 135f;
     public float rotRightMax = 210f;
     public float distanceMin = 1.2f;
     public float distanceMax = 2.0f;
     public Rect camSliderRect;
     
     private float hSliderValue = 10f;
     private float x = 0.0f;
     private float y = 0.0f;
     private bool camRotLeft = false;
     private bool camRotRight = false;
     
  
     // Use this for initialization.
     void Start (){
         Vector3 angles = transform.eulerAngles;
         x = angles.y;
         y = angles.x;
  
         // Make the rigid body not change rotation.
         if (rigidbody)
             rigidbody.freezeRotation = true;
     }
     
     void OnGUI(){
         camSliderRect = new Rect(10,10,200,40);
         hSliderValue = GUI.HorizontalScrollbar(camSliderRect, x, 1, rotLeftMax, rotRightMax);
     }
  
     void LateUpdate (){
         if (target && Input.GetMouseButton(0)) {
             x += Input.GetAxis ("Mouse X") * xSpeed * distance * 0.02f;
             x = ClampAngle (x, rotLeftMax, rotRightMax);
  
             Quaternion rotation = Quaternion.Euler (y, x, 0);
             distance = Mathf.Clamp (distance - Input.GetAxis ("Mouse ScrollWheel") * zoomMultiplier, distanceMin, distanceMax);
             
             Vector3 negDistance = new Vector3 (0.0f, 0.0f, -distance);
             Vector3 position = rotation * negDistance + target.position;
  
             transform.rotation = rotation;
             transform.position = position;
         }
     }
  
     // Clamp angle to 360 degrees.
     public static float ClampAngle (float angle, float min, float max){
         if (angle < -360f)
             angle += 360f;
         if (angle > 360f)
             angle -= 360f;
         return Mathf.Clamp (angle, min, max);
     }
 }

This, currently, rotates the camera when you have the mouse button down. You see the scrollbar moving relative to the camera. I want it so that you have to have the mouse down on the scrollbar's thumb in order to rotate the camera. Any help?