Bug 4240 Can't edit class path entry (1GKEPIF)
There is no way to edit an existing entry for a library on the Java Build Path project properties page (other than editing the .classpath file directly). NOTES: EG (9/22/2001 11:42:11 AM) this is particularly annoying for variables. we should have an Edit button when a variable is selected.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/wizards/buildpaths/ClasspathContainerWizard.java
package org.eclipse.jdt.internal.ui.wizards.buildpaths;
import org.eclipse.core.runtime.CoreException;
import org.eclipse.jface.wizard.IWizardPage;
import org.eclipse.jface.wizard.Wizard;
import org.eclipse.jdt.core.IClasspathEntry;
import org.eclipse.jdt.ui.wizards.IClasspathContainerPage;
import org.eclipse.jdt.internal.ui.util.ExceptionHandler;
import org.eclipse.jdt.internal.ui.wizards.NewWizardMessages;
/**
  */
public class ClasspathContainerWizard extends Wizard {