One other feature that the HTMLAPI provides dynamically alters subfile headings. Typically it can be used in a generic fashion for any 5250 screen.
If code like this is added to the standard SHARED layout function ApplyStandardLayout:
 
      /* Adjust the subfile headings */
 
      HTMLAPI.adjustSubFileHeadings("Arial","8pt");
 
Then the resulting 5250 screen now looks like this:

 
By making this change in your SHARED.ApplyStandardLayout: 
 
      /* Adjust the subfile headings */
 
      HTMLAPI.adjustSubFileHeadings("Arial","8pt","orange",'left',"1px solid black");  
You could cause 5250 subfile to look like this …..
 

 
 
Note: The 'shipped' intention with sub files is to make them look somewhat like list views or grids, which is exactly what this orange example does not do.