Bug 21631 JavaUI.createTypeDialog() should provide default message [dialogs]
2.0 Release If you use JavaUI.createTypeDialog() to create a new (single selection) type dialog, and then open the dialog, the open will fail silently. The dialog cannot be succesfully opened unless you send setMessage() to the dialog before you open it. This behaviour should be documented, or, preferably, a default message ("Please select a type/class/interface") should be provided.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/ui/JavaUI.java
* The caller is responsible for opening the dialog with <code>Window.open</code>,
	 * and subsequently extracting the selected package (of type
	 * <code>IPackageFragment</code>) via <code>SelectionDialog.getResult</code>.
	 * 
	 * @param parent the parent shell of the dialog to be created
	 * @param root the package fragment root
	 * @param filter the initial pattern to filter the set of packages. For example "com" shows 
	 * all packages starting with "com". The meta character '?' representing any character and 
	 * '*' representing any string are supported. Clients can pass an empty string if no filtering 
	 * is required.
	 * @return a new selection dialog
	 * @exception JavaModelException if the selection dialog could not be opened
	 * 
	 * @since 2.0
	 */
	public static SelectionDialog createPackageDialog(Shell parent, IPackageFragmentRoot root, String filter) throws JavaModelException {
		ElementListSelectionDialog dialog= new ElementListSelectionDialog(parent, new JavaElementLabelProvider(JavaElementLabelProvider.SHOW_DEFAULT));
		dialog.setIgnoreCase(false);
		dialog.setElements(root.getChildren());
		dialog.setFilter(filter);
		return dialog;
	}
	/**
	 * Creates a selection dialog that lists all packages under the given package 
	 * fragment root.
	 * The caller is responsible for opening the dialog with <code>Window.open</code>,
	 * and subsequently extracting the selected package (of type
	 * <code>IPackageFragment</code>) via <code>SelectionDialog.getResult</code>.
	 * 
	 * @param parent the parent shell of the dialog to be created