You can add ScreenTip.
First, draw an autoshape (rectangle, circle, etc) onto the slide. This
autoshape will act as the spot.
Double click on the autoshape.
This will bring up the Format AutoShape dialog box.
Set the transparency to 99%.
Set the Line Color to No line.
Click Ok.
Now, right click on the invisible autoshape.
Select Hyperlink.
Under link to, select "Place in this document".
Have it hyperlink to the current slide. You will need to perform this step
in order to add the ScreenTip.
Select ScreenTip, enter the text you want and click Ok.
Holler back if you need more help.
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Shawn Toh (tohlz)
Microsoft Most Valuable Professional (MVP PowerPoint)
Site Updated: July 23, 2006
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