Although there are several potential causes for this behavior (for example, see other FAQ questions on app-defaults), if you are using Linux, the most common one is that you are using two different versions of Motif. BX uses the Motif shared libraries found on your system. However, it is also possible you also have LessTif (a LGPL clone of Motif) installed, or some older version of Motif. If you are not careful with your link line you might find that your application is using something other than what you expected. Typically, this is easy to determine by using the "ldd" command to see which Motif libraries our programs is using. Then run the same command on the bx binary "bxb" and verify that they are the same libraries.