When a PanelCreator is used or one window is passed to PassFailJFrame, the method positionTestWindow is called:

positionTestWindow(dialog, builder.position);

Window window = builder.testWindows.get(0);
positionTestWindow(window, builder.position);

This call shows the instruction frame right away.

Later, showAllWindows() is called to display all the registered windows, which includes the instruction frame. Therefore showing the instruction could be deferred until all the windows are ready to be shown.