David John:
In native language development, some debuggers allow the user to
switch between the source code and the assembly version of that code.
 In Java 
development, it might rarely be useful to switch between the Java
source code and the byte code.  For a developer doing JSP development,
it might be 
useful to switch between the JSP version of the code, the source of
the "compiled" version, and the bytecode.  And so on.  Or, a user
might have a 
graphical way to create JSP's, which would give you four possible ways
to look at the source code (graphical view, JSP source, Java Source,
bytecode. 
perhaps also the native code that the byte code is compiled into with
a JIT)

The point here is that there may be multiple ways of representing what
is being debugged at any moment, and rather than having each debugger 
type present this in a different way, it would be good if the
debugging architecture and interface had some conventional way for
switching among these 
different representations.

*** Issue 19977 has been marked as a duplicate of this issue. ***

1) We should define UI for switching between "layers" / languages.
(like bytecode/Java/JSP)
2) We should provide some API support for this feature.
3) We should define JavaDebuggerAPI to allow delegation on Java
debugger (for JSP debugger)

done

Verified ... and Closing all issues resolved into NetBeans 6.7 and earlier.