[R] Error in layout(): Too many rows in layout

[Jeroen Van Houtte]

To display many small graphics one above the another (like Edward Tufte's 
sparklines), I'd like to use layout in the graphics package with more 
than 15 rows. 

I found that the limit of 15 is set by
#define MAX_LAYOUT_ROWS 15
in 
https://svn.r-project.org/R/trunk/src/include/Graphics.h
but I 'm not familiar enough with compilers to modify this.

Thank you for all help
Jeroen