Which JRE/JDK are you using? The earliest compatibility I can work with is 1.3 code compatibility with 1.1 class compatibility when compiling with JRE 6 in Eclipse.
I do development with eclipse and the latest JDK, but I remain aware of what features
are not available in JDK1.1. I use JDK1.1 itself to compile for delivery, not any compatibility
mode, and occasionally I actually run with JDK1.1 when looking for an obscure bug in
the deployed applet.
BTW, with all the different JREs, Browsers, and platforms out there, you can be sure that there are bugs
that will only show up in actual use. It's not just a matter of defined APIs that don't behave exactly the same;
lots of detailed behavior is unspecified, and varies seemingly at random. I speaking of things such
as if you are guaranteed to get a "mouseenter" message if the mouse enters by the window appearing