Report RFKOPR00 - C function C_GUI_SUPPORT - Returns false

Hi All,

     I am looking at a standard report RFKOPR00 which gives a classical report output. The users want ALV. I see that there is a C function call for C_GUI_SUPPORT this one returns accessibility as space. If I change it to X the output is directed to ALV Grid. Now I have two questions:

1. What is C Function. I understand its kernel funciton written in C which are kind of kernel/system parameters. but what exactly do they do?

2. What changes do I need to make to make C function return X instead of space. We are at ECC 6.0

Thanks

Anuj