Bug reported in the Debian BTS a couple years ago.

The manpage of XGetCommand states:
"If sufficient memory can be allocated to contain the string list, XGetCommand fills in the argv_return and argc_return arguments and returns a nonzero status.  Otherwise, it returns a zero status."

Looking at the code, this looks wrong. The function also returns 0 when another error occurs, no only in case of memory allocation failure. The manpage should say something like:
"If no error occurs and sufficient memory can be allocated to contain the string list, ..."

Thank you