Does an application have to know a "secret handshake" to be added to spaces

Question

It seems that some applications can be added to Spaces' "Application Assignment"s, and some can't. For instance, there's no problem with adding Firefox, whereas DOSBox is silently ignored. You go through the dialog (started by pressing the "+" under the Spaces "Application Assignment" list), navigate to the executable for DOSBox (.../DOSBox.app), click "Add," and you're returned to the System Preferences, but the application is not added to the list!
I thought it might be the base directory in which the application is found, but copying the app to /Applications didn't make it work, either.
What's the magic? Is it buried in a plist or something?

Answer 1

You can assign properties to a MovieClip dynamically.  Howvever this does not apply to all objects.  For instance, you cannot do this for Sprites and SimpleButtons.
You should declare all variables/objects.  If you are operating in strict AS3 mode, that line alone would throw  errors for two reasons... neither game1 nor mcContainer is declared.  When you are not working in strict mode, you can get away with sloppy coding.  Try the following in a file that is set up for strict mode and see what you get...
var game1:MovieClip = new MovieClip();
mcContainer = addChild(game1);