+ Puts Yes and No buttons in the message box. It is recommended to always
+ use @c wxCANCEL with this style as otherwise the message box won't have
+ a close button under wxMSW and the user will be forced to answer it.
+ @style{wxHELP}
+ Puts a Help button to the message box. This button can have special
+ appearance or be specially positioned if its label is not changed from
+ the default one. Notice that using this button is not supported when
+ showing a message box from non-main thread in wxOSX/Cocoa and it is not
+ supported in wxOSX/Carbon at all. @since 2.9.3.