Execution order of javascript function

Hi,

Ive got a function that calls another function which uses the Microsoft.XMLHTTP component to  fire a load of requests off to anther page. In the first function, i want to make a layer on my page visible, just telling the user not to navigate away from the page until the layer closes. My function is as so:

function CopySelected(theAction)
{
      var warningLayer = document.getElementById("divWarning");
      warningLayer.style.visibility = "visible";
      var controlIndex; // to hold the current ID within the loop of control objects
      var element; // to hold the value of the current control
      var numberOfControls = document.frmProjects.length; //counts all the form elements within the current form
      for (controlIndex = 0; controlIndex < numberOfControls; controlIndex++)
      {
            element = document.frmProjects[controlIndex];
            //check whether the current control is a checkbox
            if (element.type == "checkbox")
            {
                  if (element.checked == true)
                  {
                        //copy names to hidden fields
                        var theValue = element.value
                        var theRow = document.getElementById("row" + theValue);
                        if(theRow.className != "RedNormalText") {
                              if(theAction == "Close") {
                                    theRow.className = "GreyNormalText";
                                    } else {
                                          theRow.className = "BlackNormalText";
                                          }
                              }
                        var IDList = document.getElementById("hdnIDList");
                        IDList.value = IDList.value + element.value + ',';
                        CloseProject(theValue,theAction);
                        
                  } //end if(element.checked == true)
            } //end if (element.type == "checkbox")
      } //end for loop
      
      //warningLayer.style.visibility = "hidden";
      //no need to submit the form
      return false;
}

You can see in the above function that on the second line i make the layer visible, it is not for another 20 odd lines that the call to the other function is called "CloseProject(theValue,theAction);". However, the other function seems to execute before me layer is shown. Is there any way i can pause the above function until i am sure that the layer has been made visible??

Thanks in advance

Al