window.onblur = function (){
    if(showStarted){
        clearTimeout(timeOutVar);
        showStarted = false;
    }
};

window.onfoucs = function (){
    if(!showStarted){
        startShow();
    }
};

function startShow(){
    showStarted = true;
    changeSlide();
    timeoutVar = setTimeout(startShow, pauseTime);
}