var lastFocusedControlId = "";
function focusHandler(e) 
{    
    document.activeElement = e.originalTarget;
}

function appInit() 
{    
    if (typeof(window.addEventListener) !== "undefined") 
    {        
        window.addEventListener("focus", focusHandler, true);   
 
    }    
    Sys.WebForms.PageRequestManager.getInstance().add_pageLoading(pageLoadingHandler); 
    Sys.WebForms.PageRequestManager.getInstance().add_pageLoaded(pageLoadedHandler);
}

function pageLoadingHandler(sender, args) 
{    
    lastFocusedControlId = typeof(document.activeElement) === "undefined" ? "" : document.activeElement.id;
}

function focusControl(targetControl) 
{    
    if (Sys.Browser.agent === Sys.Browser.InternetExplorer) 
    {      
        var focusTarget = targetControl;       
        if (focusTarget && (typeof(focusTarget.contentEditable) !== "undefined")) 
        {            
            oldContentEditableSetting = focusTarget.contentEditable;   
            focusTarget.contentEditable = false;        
        }        
        else 
        {            
            focusTarget = null;        
        }     
                   
        targetControl.focus();      
        if (focusTarget) 
        {          
                       focusTarget.contentEditable = oldContentEditableSetting;        
        }    
    }                     
    else 
    {        
        targetControl.focus();  
                           
    }
}

function pageLoadedHandler(sender, args) 
{   
    if (typeof(lastFocusedControlId) !== "undefined" && lastFocusedControlId != "")
    {        var newFocused = $get(lastFocusedControlId);     
        if (newFocused) 
        {            
            focusControl(newFocused);        
        }   
    }
}

Sys.Application.add_init(appInit);