Sencha Architect - Add custom property in a Controller

During the last view days I was evaluating the Sencha Architect (Version 2.2.2). Most of the things that I wanted to implement were not a problem. But then I wanted to add a custom property in the controller section.

config: {
        /**
         * @private
         */
        viewCache: []
}

At first I thought no problem, that is easy. But in the end it has taken some time to find this out. So here comes the trick:

Go to the "Project Inspector". Type the name of your custom property in the search field of the config pane then click the "add" button or hit your enter key. After that you can change the type. See below: