var iter = 0;
var timer = setInterval(function() {
    if ( window.__ExtDebugger && window.Ext && window.Ext.log ) {
        clearTimeout( timer );
        window.__ExtDebugger.onReady();
    } else if ( iter > 2000 ) {
        // failed to load
        clearTimeout( timer );
        alert('failed to load ext-debug');
        window.__ExtDebugger = null;
    }
    iter++;
},100);