Bug 123496 [IDE] Use operation validation API for IDE actions
We should use the Resources/Core operation validation API in the IDE actions for manipulating resources.
bundles/org.eclipse.ui.ide/src/org/eclipse/ui/ide/IDE.java
* @param file the file
     * @param editorID the editor id
     */
    public static void setDefaultEditor(IFile file, String editorID) {
        try {
            file.setPersistentProperty(EDITOR_KEY, editorID);
        } catch (CoreException e) {
            
        }
    }
    /**
	 * Returns the default editor for a given file. This method will attempt to
	 * resolve the editor based on content-type bindings as well as traditional
	 * name/extension bindings.
	 * <p>
	 * A default editor id may be registered for a specific file using
	 * <code>setDefaultEditor</code>. If the given file has a registered
	 * default editor id the default editor will derived from it. If not, the
	 * default editor is determined by taking the file name for the file and
	 * obtaining the default editor for that name.
	 * </p>
	 * 
	 * @param file
	 *            the file
	 * @return the descriptor of the default editor, or <code>null</code> if
	 *         not found
	 */
    public static IEditorDescriptor getDefaultEditor(IFile file) {
		return getDefaultEditor(file, true);
    }