I think I am beginning to understand the enormous depth of the problem. If I understand correctly, the current CC version is "2014.1" (i.e., the InDesign version is 10.1.*). Since Extension Builder 2.1 seems only able to produce an MXI/ZXP up to InDesign 9.9, I think I am in deep, deep trouble.
Is there any solution with Extension Builder 2.1, or must I install Extension Builder 3 and rewrite all my tens of thousands of lines of code in JSX (we wrote our Extensions in ActionScript 3)?
TIA for any advice,
One last addition:
I saw the hack on page Adobe Extension Builder and Creative Cloud 2014
The problem is that that hack it doesn't seem to work if you use Host Adapters (and we do).
All help appreciated,
for the ZXP packaging, this page might help: http://www.davidebarranca.com/2014/05/html-panels-tips-10-packaging-zxp-installers/
Mind you, I can't tell you whether the latest InDesign version (10.x aka CC 2014) has already dropped the Flash panel support or not. Photoshop for instance did, starting from CC 2014 - but we've been warned in advance that PS would have been the avant-garde among CC apps.
If you have ActionScript code (and not ExtendScript) I'm afraid you're stuck - porting back to ExtendScript is the only choice.