title: Edit contained label dynamically based on which tab is selected
body: <p>pretty new to vb and I want to get a tab control working. 
  so far I have the form with a tab control on it, there are 5 tabs each with a label contained in the tab-page.
  I want to have a button outside of the tab that changes on the form. when clicked the button will change the text of the label based on which tab is currently selected. I know it should be possible to do this, I'm not too sure where to start. </p>