I’ve updated to the latest and it doesn’t seem to work at all for me (JavaScript):
var tabBar = me.getTabBar(),
initialConfig = card.getInitialConfig(),
tabConfig = initialConfig.tab || {},
tabTitle = initialConfig.title,
tabIconCls = initialConfig.iconCls,
index = card.getIndex(),
tabs = tabBar.getItems(),
cards = me.getInnerItems(),
currentTabInstance = (tabs.length >= cards.length) && tabs.getAt(index),
tabInstance;