>But my question is a little "deeper". In its most simple form my question is: Are we at the mercy of MS keeping up-to-date with Netscape, Opera, etc. in order for this to truly do a BEST RENDER job on each browser?

No, you are not at MS's mercy. You can always subclass and write the render code yourself.

I think getting hung up on "BEST RENDER". The point isn't to "BEST RENDER" but to "WORK". If a JScript works differently from IE to NS, the control is rendered to work.

>Hypothetically I could have a wonderful application that is rendering well and acceptably and predictably on 3 versions of IE, 3 versions of Netscape and 2 versions of Opera. Now MS issues a 'maintenance' item (service pack or Windows "fix" or whatever to support best-rendering in the just released version of Netscape. I apply it.
>--- Can this affect my previously rendering-OK other 3 existing Netscape users, making it bad where it was good?

WIth a simple update of the .NET Framework? No, you need to check out how versioning of assemblies works and the global assembly cache. Recompiling with newer controls theoritically could, but I doubt they'd let that happen.

>------ Assuming so, then I'd want to fall back to the old (proper) one. Is it packaged so that I can do this?

You can also hardwire what browser you want to target. THats just a property of teh control.

>--- How will it handle the lastest version of a browser if I haven't yet installed (maybe MS hasn't yet delivered) best-render support for the latest version of Netscape?

If the browser is newer, I doubt you'd have a problem. Think about it. No browser maker woudl make their product incompatbile with rest of the internet.

>Why would I think that MS would care to spend the time and money necessary to keep OTHER browsers doing a best-render job?

Because they already have. If you're not impressed with the amount of work they've already put into this, you never will be.

>In other words, how can I protect myself from MS letting OTHER browser rendering become poorer and poorer, thus pushing me and everyone else to IE?

If you want to be Chicken little, don't rely on the server controls in the .NET Framework and do it all yourself. You'd better start now. Plain and simple.

Otherwise turn off the browser rendering an only output one type of HTML, lowest common denominator. Personally, I don't see why you'd want to do this when the work is already done, but I recognize your concerns.