how to only display Preprocessor Directives with C/C++

[dzp277135246]

The version I use for 2016 v21,Thanks!!

[dzp277135246]

I set the view->selective display->preprocessor diectives, but this feature does not scan the macros defined in other documents. How to solve the problem?
e.g
in a.c
#ifdef MACROS
int a = 0;
#endif

in b.h
#define MACROS

In this case,click "Scan for Defines" button in Selective Display dialog,SlickEdit does not scan the macros defined in b.h. How to solve the problem? Thanks!!