How do I get html data to show in an panel when I click an item in my listbox? gwt

I am using eclipse with the google web toolkit plugin and have built a widget which has a ListBox and a horizontal Split开发者_Go百科LayoutPanel. I want to be able to click on an item in my list box and have it display the HTML in the top pane of my split panel. I think I need to setup click handler but I am not quite sure how to go about this. Please give me a push in the right direction.

Add a ChangeHandler to the listBoxInstance. In the onChange, get the selected value using getSelectedIndex()/getValue(). Process as required.