1. Open a new document by clicking on File -> New. Goto Insert -> New Symbol and give name to this symbol, 'Ripple' and set its behavior to Movie Clip. Change the layer 1 name to 'Ripple'.
2. Now on frame 2 of ripple layer and at the center of the circle, create a small circle with stroke color set to light blue and fill color to none. As shown in the fig I.R.1.
3. Extend frames of ripple layer to 30 and create an animation that enlarges this circle and at the last frame the circle gets disappear. Use Alpha to zero at the last frame for this purpose. (see spotlight effect).
4. Goto Insert ->New Symbol once again but this time select button in behavior and name this symbol as 'Invisible Button'.
On Layer 1 click under 'Hit' and press f6.
5. Now grab a rectangle with any color as color doesn't matter while you are using invisible buttons. Draw an appropriate sized rectangle at the center of the screen around plus sign.
6. Go back to ripple symbol.
7. Add a new layer and change its name to 'Invisible Button'. Now open up the library and drag invisible button on stage. Make sure that you are on layer of Invisible Button.
8. Click on frame2 and Resize the Invisible button to just cover the small circle at the center. Note that invisible button will be appearing in light blue color. That's normal. See fig I.R.3
9. You have to stop the timeline on first frame of the ripple layer. For this purpose we will be using action script on frames. You can also use action scripts on buttons as well. Click on the first frame of ripple layer and then right click, click on Actions.
10. Goto Actions -> Movie Control -> Stop to stop the ripple layer. Click on the Invisible button and then right click, click Actions. Again click on the '+' sign and goto Action -> Movie Control -> Play. Click on the scroll bar on the right side to up. Click on 'on Release'.
11. The events window will be opened in front of you. Now check the Roll Over event. Uncheck all the others.
12. Close the actions panel. Go back to scene 1 and change the layers name to 'Ripples'
Now open the library and drag and drop Ripple symbol from it on to stage.
Drop as many symbols as you can.
You can download source file here.
More Flash & Swish: 
