There is a bug in the current version, which is corrected in the following beta:
However, there is still an unresolved issue. The underscore is considered as a letter (see http://www.regular-expressions.info/wordboundaries.html )
!define SHOW_TYPE(x) my_x
won't work because "mu_x" is seen a single word, just like "myx"
!define SHOW_TYPE(x) my-x
will work, because x is here alone.
Is it a real issue for you ?