code: public boolean isTabVisible(final int idx) {
  		WTab tab = getTab(idx);
  		Container tabParent = tab.getParent();
  
  		if (tabParent instanceof WTabGroup) {
  			return tab.isVisible() && tabParent.isVisible();
  		} else {
  			return tab.isVisible();
  		}
  	}
docs: Indicates whether the tab at the given index is visible.
  
  @param idx the index of the WTab to test.
  @return true if the tab at the given index is visible, false if it is invisible.