The run-single target is a simple target without support for the use of the
command line arguments specified in the project settings.  I use run-single to
run one of a handful of tools/classes in my projects which all use the same
particular set of configuration values from the command line etc.  These include
things like -Djava.security.policy -Djava.util.logging.config.file and other
things which really do need to be specified.  I find my self having to make
adjustments for this issue in all of my projects that I allow Netbeans to manage
the ANT generation for.  I believe it should do this itself.  Something like

    <target name="run-single" depends="init,compile-single">
        <fail unless="run.class">Must select one file in the IDE or set
run.class</fail>
        <j2seproject1:java classname="${run.class}">
            <customize>
                <arg line="${application.args}"/>
            </customize>
        </j2seproject1:java>
   </target>

which mirrors the "run" target would be enough, but I also think it should not
compile anything.  By just doing compile-single, the user sees some build
activities, and becomes comfortable that the IDE is taking care of his/her
needs.  But, the user really should have to make sure that the appropriate build
steps have been taken.  Also, not doing the compile makes things faster when I
am just going around making changes and running compile-single with F9 myself
already.