Checks to see if [method@GutterLines.add_qclass] was called with the quark denoted by @qname for @line.
a line number starting from zero
a #GQuark containing the class name
%TRUE if @line contains @qname
See Implementation
Checks to see if [method@GutterLines.add_qclass] was called with the quark denoted by @qname for @line.