click vs long press (drag) help?

Hi all.

I have a drag-able menu in my game which scrolls horizontally from left to right when the user drags the mouse in the given direction. The scrolling begins when the user touches anywhere on the screen, and this works well. I also have a list of boxes which make up the menu, which will change the background when pressed/clicked. I added an OnMouseUpAsButton function to ensure that when the box is clicked and the mouse button is lifted the background would change as indicated. I would like however to detect whether the click was a short click on the box to change the background, or if it was a long press which would be used to drag the menu left to right. Here is the code that I am trying -

 var temps : float;
 
 
 function OnMouseUpAsButton () {
 if ((Time.time - temps) < 0.2){
 if (statics.levelback >= level){
 background = number;
 }}
 if (Time.time - temps > 0.2){
 }
 }

The problem that I have right now is that when I long press on the box and drag the mouse left or right, the menu scrolls, but as soon as the mouse is lifted the background is changed. I would like that the player would instead have to click the particular box (short click with no drag) in order for the background to be selected. Can anyone help with this?