Controlling the visibility of objects
You can hide an object on a slide, and define conditions that must be satisfied for the object to be displayed.
The following example illustrates how to hide an image on a slide until the user clicks the Show Image button.
Select Insert > Image to insert an image on the slide.
In the Property Inspector, type a name for the image in the Name text box. For example, My_Image.
Clear the Visible check box.
Select Insert > Standard Objects > Button.
In the Action area of the Property Inspector, select Show in the On Success list, and then select My_Image in the Show list.
When you play the movie, the image appears only when you click the button.