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/SourceContainerWorkbookPage.java
} else if (field == fProjectRadioButton) {
			if (fProjectRadioButton.isSelected()) {
				fIsProjSelected= true;
				updateClasspathList();
			}
		} else if (field == fFoldersList) {
			updateClasspathList();
		}
	}	
	
		
	private void updateClasspathList() {
		List cpelements= fClassPathList.getElements();
		
		List srcelements;
		if (fIsProjSelected) {
			srcelements= new ArrayList(1);
			if (fProjectCPEntry == null) {
				
				fProjectCPEntry= newCPSourceElement(fCurrJProject.getProject());
			}
			srcelements.add(fProjectCPEntry);
		} else {
			srcelements= fFoldersList.getElements();
		}
		boolean changeDone= false;
		CPListElement lastSourceFolder= null;
		
		for (int i= cpelements.size() - 1; i >= 0 ; i--) {
			CPListElement cpe= (CPListElement)cpelements.get(i);