How to check if a group contains a specific control ?

[jbv at souslelogo.com]

Hi list,

Is there a quick way to check if a group contains a specific control,
something like :
if there is a fld "xyz" in grp "abc" of this cd

I tried many things but it always generates an error.
So far, the only way I can think of is to maintain a custom prop
for each group, featuring a string that is the list of all controls
names of the group.

Thank you in advance.
jbv