function updateEngine(thissay){
   engine = thissay;
   updateButtons(thissay);
}

function swapBack(buttonOver){
   if(engine != buttonOver){
      document.getElementById(buttonOver).style.backgroundImage="url(images/tab2.png)"
   }
}

function swapOut(buttonOut){
   if(engine != buttonOut){
      document.getElementById(buttonOut).style.backgroundImage="url(images/tab1.png)"
   }
}

function updateButtons(buttonClicked){
   document.getElementById("tab1").style.backgroundImage="url(imgs/images/tab2.png)"
   document.getElementById("tab1").style.backgroundImage="url(imgs/images/tab2.png)"
 document.getElementById("tab2").style.backgroundImage="url(imgs/images/tab1.png)"  
 
   document.getElementById(buttonClicked).style.backgroundImage="url(images/tab2.png)"
}