When you click on the 0001-windows-7.btn file on the Project pane, a fully working preview of the button appears on the Preview pane. (If the Preview pane isn't visible, use the View > Panes > Resource Preview menu item to toggle it back on.)
You can use the Preview pane to see how the button will respond to the mouse in your completed application.
Tryi ng i t out i n the Previ ew pane