Just a preface: I'm coming at this from the perspective of a professional Flash character animator. I've worked on two TV shows and one big-budget online virtual world/game and I've been using Flash professionally since MX 2004. I've also written a lot of JSFL commands and done a little actionscript programming (I used to be a software engineer, so the programming comes pretty maturally to me).
So with that said, here are some of the things that I'd really like to see in the next version of Flash, approximately in order from more to les important:
3. Stability and user friendliness. Please, guys, spend a little more time on polish and leave off the one or two extra cool features that you were thinking about throwing in.
13. Color management. I can't emphasize this one enough. COLOR MANAGEMENT! Take a look at Toon Boom Studio for what I'm talking about. Particularly in large projects, the ability to have a real color palette, rather than just having each shape have an RGBA value, would be incredibly useful. That way if I decide I don't like the color of a character's shirt I could just change the shirt color palette entry and it would automatically update every shape in the file that used that palette entry. An extra bonus, though less important, would be to be able to control it from Actionscript -- to be able to change a palette entry dynamically at run-time.
5. non-affine transforms for symbols. Particularly, we want trapezoidal/perspective skew! I've heard SO many people talk about wanting this. I was hoping that the 3D stuff in CS4 would allow it, but no such luck. While it's theoretically possible the controls just aren't set up to allow it.
1. Make EVERYTHING in the Flash authoring environment scriptable. Currently there are a number of things that can be neither scripted nor given a keyboard shortcut, (for instance the onionskinning controls).
2. Make Flash remember its maximized status from the previous session (this is a problem in many Adobe products).
4. Real hardware 3d acceleration.
6. Refine the JSFL API to be more thorough and consistent (see also #1). Make it so that everything you can do in JSFL happens in a way that makes sense. For instance, a couple problems I had recently: delete a shape from the stage and then draw a new one with Path.makeShape() and the new shape is created as if the old one were still there (with extra vertices at edge intersections); and Path.makeShape() won't create cubic paths -- it automatically converts cubic contours to quadrilateral ones.
7. Speaking of types of paths: Make the distinction between quadrilateral and cubic paths clearer to the user. Most people I talk to don't have any idea what the difference is, or that cubic paths are likely to produce more vertices than they expect in the final SWF. In fact, I think you should consider ditching the distinction entirely, at least from the user's perspective. Make every path in the authoring environment cubic, and just convert them to quadrilateral (if you must) on export. This'll relieve a lot of annoyance from users unexpectedly finding that their shape they just created very frugally suddenly has three times as many vertices.
8. Make bones work better on raw shapes. In fact, make them work more like Maya: each bone should affect each vertex to a degree decidable by the user. Currently bones affect each vertex either 0% or 100%, which means that, for instance, it's nearly impossible to get a smoothly curving snake.
9. Add at least one new fill style: we have radial blending, but the major one we're missing is the OTHER kind of radial -- with rays shooting our from a center. Perhaps less realistically, I can't tell you how much it would rock to be able to use a path-based color blend -- where the blend actually follows an arbitrary path (like what you can do in Synfig -- www.synfig.org).
10. Add precision to the stage. Currently it's very hard to position things when zoomed in close, and display artifacts are show up on curves, where they get flattened out for no apparent reason. I think the display artifacts are new to CS4, so perhaps it's just a bug that needs to be worked out in the new display engine? But the current situation is a real pain -- where any symbol that's created relatively small will unavoidably contain rendering and positioning issues.
11. A feature that's been missing (and sorely missed by TV animators) since Flash 8 is the ability to smoothly copy and paste from Flash to Illustrator. There's absolutely no reason this shouldn't be an easy task, and I'm still confused as to why it disappeared from MX 2004 to Flash 8. It's extremely useful for applying art brushes to paths or animating 3D door swings in Illustrator and then bringing the art back into Flash.
12. For that matter, what about art brushes in Flash? I realize they would be heavy in the SWF -- either in rendering time or in space used -- but you've already got stipled brushtrokes, and aren't those just as heavy? Art brushes would be INCREDIBLY useful to animators and designers.
14. Engage with the people who use Flash. Get some dialogue going on between users and developers. Most Flash users I meet (admittedly mostly character animators and character rig builders/designers) have very specific wishes for Flash, and for the most part they coincide very nicely. Yet release after release we don't see any of the changes, features, or bugfixes, that seem the most obvious.