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/LibrariesWorkbookPage.java
protected void okPressed() {
			fResult= null;
			if (fCreateFolderField.isSelected()) {
				fResult= createNewClassContainer();
			} else if (fAddFolderField.isSelected()) {
				fResult= chooseClassContainers();
			} else if (fAddContainerField.isSelected()) {
				String selected= fCombo.getText();
				for (int i = 0; i < fDescriptors.length; i++) {
					if (fDescriptors[i].getName().equals(selected)) {
						fResult= chooseContainerEntry(fDescriptors[i]);
						break;
					}
				}
			}
			if (fResult != null) {
				super.okPressed();
			}
			
		}
		
		public CPListElement[] getResult() {
			return fResult;
		}
	}
	
		
					
	
	private static class SourceAttachmentDialog extends StatusDialog implements IStatusChangeListener {