Converting MMExecute to ExternalInterface.call

I have an old, complicated, custom WindowSWF panel which was written in AS2 and makes extensive use of MMExecute to read and modify the Flash environment. The panel works fine in Flash 8, CS4, CS5.5, and CS6.0. I have given it to someone on Animate CC, and it doesn't work. I'm trying to resolve this, even though I don't have Animate CC to test on.

The symptom reported to me is that although the user interface is working correctly, any time a value is supposed to be populated from the Flash environment, it's blank or NaN.

From what little information I can find online, MMExecute was dropped from Flash CC and later put back with very limited functionality. To get full functionality, the recommendation is to switch to ExternalInterface.call. (source) I also see that the callback feature of ExternalInterface doesn't work with AS2, but this is fine, I would think — MMExecute doesn't do that at all.

So I started to try to make the switch. I have a long string of JSFL code which defines JSFL functions. This code was called with MMExecute, but I can switch it to ExternalInterface.call, and then I can call these functions using MMExecute. So at least to some degree, ExternalInterface.call is working.

But if I try to get ExternalInterface.call to do anything directly, it doesn't work. ExternalInterface.call("fl.trace('test');"); does nothing. ExternalInterface.call("fl.createDocument();"); does nothing. If I attempt to get a return value, such as var clickY:String = String(ExternalInterface.call ("fl.tools.penDownLoc.y;")); I get null.

Is anyone able to confirm that replacing MMExecute with ExternalInterface.call is indeed the way to resolve the Animate CC problems? And if so, why can't I get it to run simple commands or to return values?

oh wow, people still maintain ide components. adding myself here in case someone smarter will reply )

is your rel name Mike Lyda? I saw this Mike asking the same question a month ago.

Nope, I'm Jerry. I considered this tool done in 2009 or so, but I still use it. I've hired someone to help me with something and the tool doesn't work for him in Animate CC, so I'd like to be able to fix it. The scarcity of information online makes it tough. Some things hint that maybe it would help if I rewrote the whole thing in AS3, but I don't even want to think about doing that unless I knew it would solve the problem.

I take it Mike didn't find an answer either? I can't find the post.

I've reposted this on the Adobe forums. I'll follow up here if I learn anything.