There are two ways. If what is on the layer is a symbol, and it has a keyframe, you can select that frame, then select the object on the stage, and then using the effects panel, you can set the _alpha with that.
Sometimes, like if you have a tween where you want it to go from 100% to 0% visiblility, this is the way to do it.
The other way is this. It’s a little more complex, but it’s the prefered method for file size.
Copy the frames from one of the layer.
Use menu option “Insert/Create new symbol” to bring up the new symbol dialogue.
Choose “movie clip” and give it a library name that is discriptive.
Go into the library and double click on it to edit it. Paste the frames in this symbol.
Do this with each of the three layers in each of their own movie clips.
you can now cut the frames out of the layers on your main timeline. From the library, drag instances of each of the three movie clips to the stage, in one layer or in three… it really doesn’t matter.
Now select each movie clip and in turn, give each an “Instance” name in the properties panel. (If you have a movie clip selected, you will see the text field there for entering an instance name… labeled with <instance>.)
Now, you can call to each symbol as you like. For instance, if you wanted a symbol to be invisible, and for any button inside it to be disabled you could use this command
or you could set the _alpha (which does not deactivate buttons within the movie clip), with this command
I find this latter method to work best for me, but it’s really personal choice.
For the record, “_visible=false;” saves processor speed over “_alpha=0;”… so if you’ve got a lot moving on the stage at once, and things are slowing down, it’s good to think about either removing movie clips, or making them _visble=false;
Hope that helped.