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
/**
	 * 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 if <code>determineContentType</code> is
	 * <code>true</code>.
	 * <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
	 * @param determineContentType
	 *            determine the content type for the given file
	 * @return the descriptor of the default editor, or <code>null</code> if
	 *         not found
	 * @since 3.1
	 */
    public static IEditorDescriptor getDefaultEditor(IFile file, boolean determineContentType) {
        
        IEditorRegistry editorReg = PlatformUI.getWorkbench()
                .getEditorRegistry();
        try {
            String editorID = file.getPersistentProperty(EDITOR_KEY);
            if (editorID != null) {
                IEditorDescriptor desc = editorReg.findEditor(editorID);