Menu bars and dialog boxes can be converted from Windows resource files, using Petr Smilauer's resource parser (Windows version of wxBuilder only). Menu bars convert well, but due to the differences between wxWindows panel items and Windows controls, dialog boxes convert less well.
Use the Load Windows resources option from the Edit menu. This opens a dialog box from which .RC files may be loaded, or added to the existing database of resources. Once the resource file has been loaded, quit from this dialog and use the Convert menu bar or Convert dialog option from the Edit menu.