The 1.1.2 release of the plug-in uses javax.swing.* classes
instead of the com.sun.java.swing.* classes. The 1.1.1
release included com.sun.java.swing.*

Result: plug-in 1.1 applets developed with 1.0.3 swing components
cannot initialize because the plug-in no longer contains
those swing components.

The 1.1.2 release notes say that support for swing 1.1 was
added in that "maintainance release" but do NOT say that
support for swing 1.0.3 was dropped.