[syslinux] Using the cat.c32 sample as a functional equivalent to the FN keys in vesa mode

[David W. Koeller]

I have been hacking around with the new vesa boot menus and I had a 
couple questions.

Do you currently have a method to set the SHADOWING options that are 
coded in menumain.c from within the menu config file?  I saw something 
in readconfig that looked like you were parsing single characters to map 
to SHADOW_NONE, etc. constants for these parameters, but I did not 
follow it.  The default shadowing looked horrible on a white background 
image I was using.  I managed to turn it off by recompiling the 
menumain.c with different color schemes.

I have modified the cat.c32 sample under com32 to invoke a vesa console 
video mode and set the color table accordingly based on code from 
menumain.c.  This can then be called from within vesamenu.c32 to cat a 
file containing the help text for optional kernel parameters that could 
be passed at the command prompt.  I would really like to add the 
equivalent of a boot: prompt at the bottom of this code in the context 
of vesa so it behaves similar to the traditional FN keys with .msg 
files.  I currently just issue a get_key call at the end of the cat.c 
file and inform the user to hit a key to get the boot: prompt which 
works.  The only drawback is that the help is now gone when they go to 
type since we are back in a different video mode.

On the same note, is there a return code or call sequence I can invoke 
from within cat.c to reload the default calling vesamenu.c32 if the user 
choses the cat.c32 help and then wants to return to the main menu 
without first hitting enter through the boot: parameter?

All in all, the new vesa menus are pretty awesome looking.  Great work.

Dave