Use the attached document or
 -create a shape
 -assign a custom animation e.g. 'fly in' that starts with mouse click
 -open 'Effect Options' dialog and choose in addition: After Animation 'Dim with
color'  and choose a color
 - create a second shape
 - add an effect to the second shape that starts per mouseclick (e.g. 'fly in') 
 - start the presentation
-> after first click the first shape flies in and changes the color
instead the color should not be changed until a second mouse click

If in a different scenario the second effect starts automatically after the
first effect, the color change should happen when the second effect starts and
not on next mouseclick.