Bug 120544 [build path] Editing external source folder does not persist
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/wizards/buildpaths/SourceContainerWorkbookPage.java
} else {
			AddSourceFolderWizard wizard= newSourceFolderWizard(elem, fFoldersList.getElements(), fOutputLocationField.getText());
			OpenBuildPathWizardAction action= new OpenBuildPathWizardAction(wizard);
			action.run();
		}
	}
	private void editAttributeEntry(CPListElementAttribute elem) {
		String key= elem.getKey();
		if (key.equals(CPListElement.OUTPUT)) {
			CPListElement selElement=  elem.getParent();
			OutputLocationDialog dialog= new OutputLocationDialog(getShell(), selElement, fClassPathList.getElements());
			if (dialog.open() == Window.OK) {
				selElement.setAttribute(CPListElement.OUTPUT, dialog.getOutputLocation());
				fFoldersList.refresh();
				fClassPathList.dialogFieldChanged(); 
			}
		} else if (key.equals(CPListElement.EXCLUSION) || key.equals(CPListElement.INCLUSION)) {
			EditFilterWizard wizard= newEditFilterWizard(elem.getParent(), fFoldersList.getElements(), fOutputLocationField.getText());
			OpenBuildPathWizardAction action= new OpenBuildPathWizardAction(wizard);
			action.run();
		}
	}
	protected void sourcePageSelectionChanged(DialogField field) {
		List selected= fFoldersList.getSelectedElements();
		fFoldersList.enableButton(IDX_EDIT, canEdit(selected));
		fFoldersList.enableButton(IDX_REMOVE, canRemove(selected));
		boolean noAttributes= containsOnlyTopLevelEntries(selected);
		fFoldersList.enableButton(IDX_ADD, noAttributes);
	}