Note that this needs more precise formulation: for Java source roots
only? Also for web context roots (which could be impossible, depending
on how things are set up)?

It should be possible to mount separate Java source roots, as well as
non-Java source roots. A J2EE app can have servlets, beans, and EJBs,
which need to be compiled to different target directories. (The Java
source may reside completely outside the deployed J2EE app directory
structure.) I see the need for at least three different Java source
mappings and one non-Java source mapping.

1. Servlets need to be compiled to WEB-INF/classes.
2. Beans need to be compiled to WEB-INF/classes (as .class files if
the container will support dynamic reloading) or to WEB-INF/lib (as a
.jar file).
3. EJBs need to be compiled to a different directory as a jar file.

These source files may be in subdirectories of one mounted filesystem
or separate mounted filesystems. In general they will be
subdirectories of one filesystem, since the source code for one J2EE
app will usually be kept in the same directory structure, organized by
package name (e.g., com.foo.servlet.*, com.foo.beans.*,
com.foo.ejb.*). Then you would specify that a certain subdirectory is
compiled (as either .class files or one .jar file) to a certain other
mounted filesystem, or subdirectory of a mounted filesystem. It should
be possible to specify these mappings without having to use an Ant
script. I believe in NB 3.5/3.6 the project tab let you do something
pretty similar to this. I think it was on the right track--it just
needed some more enhanced functionality to cover everything described
here.

JSP/HTML files are most conveniently edited directly inside the
deployed app, so that changes can immediately be viewed in the
browser. Thus, it should be possible to mount the web app directory
that resides in the deployment directory. Depending on the source
control system in use, it may be possible to check those files out
directly to the web app directory.

fixed?

Fixed.

build 20050607