static/ext/src/Ext-more.js
function(callback, scope, args, delay){
        if(Ext.isFunction(callback)){
            args = args || [];
            scope = scope || window;
            if (delay) {
                Ext.defer(callback, delay, scope, args);
            } else {
                callback.apply(scope, args);
            }
        }
    }
function(callback, scope, args, delay){
        if(Ext.isFunction(callback)){
            args = args || [];
            scope = scope || window;
            if (delay) {
                Ext.defer(callback, delay, scope, args);
            } else {
                callback.apply(scope, args);
            }
        }
    }
function ( callback , scope , args , delay ) { if ( Ext . isFunction ( callback ) ) { args = args || [ ] ; scope = scope || window ; if ( delay ) { Ext . defer ( callback , delay , scope , args ) ; } else { callback . apply ( scope , args ) ; } } }
Execute a callback function in a particular scope. If no function is passed the call is ignored.

For example, these lines are equivalent:

Ext.callback(myFunc, this, [arg1, arg2]);
Ext.isFunction(myFunc) && myFunc.apply(this, [arg1, arg2]);

@param {Function} callback The callback to execute
@param {Object} [scope] The scope to execute in
@param {Array} [args] The arguments to pass to the function
@param {Number} [delay] Pass a number to delay the call by a number of milliseconds.
Execute a callback function in a particular scope . If no function is passed the call is ignored .