Problem creating rollover buttons

I want some areas of my background picture to behave as roll-over buttons. (A bit like an image map). So I created a second copy of the background where the areas have a slightly different color ("glow" effect).

Now I carefully position the "rollover" background exactly on top of the plain background, break it apart and remove all but the area that must become a button. I create a button Symbol from that area.

So far so good. When I toggle visibility of the layer containing the rollover image, I can see that the images are still exactly on top of each other. But in the generated swf file, the rollover "moves" with respect to the background.

Any suggestions? Are there better ways to create rollovers on an "image map" ?

Thanks.

Sounds like you made a mask.

But im not even close to being qualified to answer. Good luck.

I experimented a bit more and I think my problem is due to a roundoff error in the Flash engine.
When I construct my button while zoomed out to 50%, the result does not have the problem I described.

Is there any way to force Flash to use integer coordinates? (I'm using Flash 4).

Hi, you can use:

Rounding to specific decimal places in Flash

I know exactly what you are talking about... sometimes things line up fine but then you export and they don't. I don't have a sure fire answer... I think sometimes it depends on what format you import the file as. I would recommend fidding with:
- toggling "allow smoothing" for each bitmap
- making sure all objects don't have fractional x,y values
- possibly put the rollover objects to 99% or 101% (I believe this fixes a weird bug where objects sometimes get a line of double-pixels in them)
- related to previous one... try moving your objects so the center point is in the upper left rather than the center of the bitmap... I think flash has a bug where it "smooths from the center" so it is better to have the center point in a corner.

Also, if your objects are things that float over a background... try putting them on a separate layer with one frame normal and one frame glowing. Since in both frames they are separate objects floating over the background they won't have to line up with the background exactly... hope that makes some sense.

I finally managed to solve my problem by creating the buttons while zoomed out to 50%. I guess that got around the round-off error.