lib/Ext/navigation/Bar.js
function() {
        var text = this.backButtonStack[this.backButtonStack.length - 2],
            useTitleForBackButtonText = this.getUseTitleForBackButtonText();

        if (!useTitleForBackButtonText) {
            if (text) {
                text = this.getDefaultBackButtonText();
            }
        }

        return text;
    }
function() {
        var text = this.backButtonStack[this.backButtonStack.length - 2],
            useTitleForBackButtonText = this.getUseTitleForBackButtonText();

        if (!useTitleForBackButtonText) {
            if (text) {
                text = this.getDefaultBackButtonText();
            }
        }

        return text;
    }
Returns the text needed for the current back button at anytime.
@private