Cancel, stop script

Hello everyvody

A little help..

I make this simple test script for Illustrator

At this point even if I press the cancel button the script continues to work..

How to make "cancel" button to stop the script. ...?

Thanks,

Nick Riviera

var doc = app.activeDocument;
                 
function panel(){
    var unit;  
    var units = ['mm',];   
    var panel = new Window("dialog", "test", undefined, { borderless: false });
        panel.alignChildren = "left"; 
       
    var r0 = panel.add ("group");
    r0.add ('statictext {text: "unidades", characters: 8, justify: "left"}');
    var dims = r0.add("dropdownlist", undefined, units);
    dims.selection = dims.items[0];
   
    var r1 = panel.add ("group");
    r1.add ('statictext {text: "x", characters: 8, justify: "left"}');
    var w = r1.add("edittext",undefined,"100");
    w.characters = 10;
    
    var r2 = panel.add ("group");
    r2.add ('statictext {text: "h", characters: 8, justify: "left"}');
    var h = r2.add("edittext",undefined,"50");
    h.characters = 10;
    
    var r6 = panel.add ("group");
    r6.add("button", undefined, "OK");
    r6.add("button", undefined, "Cancel");
    
     unit = dims.selection.text;  
     x = Number(new UnitValue(w.text + " " + unit).as('pt'));
     y = Number(new UnitValue(h.text + " " + unit).as('pt'));
    
    
    panel.show(); 
}

function cR(){
   doc.rulerOrigin = [0,0]; 
   var layer2 = doc.layers.add();
                layer2.name = "test";
                rectangle = layer2.pathItems.rectangle(x, 0, y, x);
}
    
var rS = panel();
cR(rS);