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
private SelectionButtonDialogField fFolderRadioButton;
	private ListDialogField fFoldersList;
	private CPListElement fProjectCPEntry;
	
	private StringDialogField fOutputLocationField;
	
	private boolean fIsProjSelected;
	public SourceContainerWorkbookPage(IWorkspaceRoot root, ListDialogField classPathList, StringDialogField outputLocationField) {
		fWorkspaceRoot= root;
		fClassPathList= classPathList;
		fProjectCPEntry= null;
		fOutputLocationField= outputLocationField;
		
		fSWTControl= null;
				
		SourceContainerAdapter adapter= new SourceContainerAdapter();
				
		fProjectRadioButton= new SelectionButtonDialogField(SWT.RADIO);
		fProjectRadioButton.setDialogFieldListener(adapter);
		fProjectRadioButton.setLabelText(NewWizardMessages.getString("SourceContainerWorkbookPage.rb1.label")); 
						
		fFolderRadioButton= new SelectionButtonDialogField(SWT.RADIO);
		fFolderRadioButton.setDialogFieldListener(adapter);
		fFolderRadioButton.setLabelText(NewWizardMessages.getString("SourceContainerWorkbookPage.rb2.label")); 
		
		String[] buttonLabels;
		int removeIndex;
		buttonLabels= new String[] { 
			 NewWizardMessages.getString("SourceContainerWorkbookPage.folders.addnew.button"), 
			 NewWizardMessages.getString("SourceContainerWorkbookPage.folders.addnew.addexisting.button"),