One of the animation effects available in Powerpoint 2010 is 'Blink', but there doesn't seem to be an msoAnimEffect which corresponds to this. Is there a way to add this effect programmatically, or do I have to write a much more involved macro to make
a text box appear and disappear?
The solution was to make a copy of the textbox, move it off the slide and set it to blink 'With previous' and 'repeat until the end of the slide'. Then, instead of trying to add a blinking effect to the original textbox, I just set its visibility to false
and moved the blinking copy to the original's co-ordinates.
To cancel the blinking effect, I set the copy's .top parameter to -75 and make the original visible again.