Here's confirmation obtained using gdb with evince:
Breakpoint 5, add_cups_options (key=0x7faa10a346b0 "cups-PageSize", value=0x7faa11235a20 "Custom.595.28x841.89", user_data=0x7faa11041090) at /build/buildd/gtk+3.0-3.4.2/./modules/printbackends/cups/gtkprintbackendcups.c:521 521 in /build/buildd/gtk+3.0-3.4.2/./modules/printbackends/cups/gtkprintbackendcups.c ... Breakpoint 6, add_cups_options (key=0x7faa10a346b5 "PageSize", value=<optimized out>, user_data=<optimized out>) at /build/buildd/gtk+3.0-3.4.2/./modules/printbackends/cups/gtkprintbackendcups.c:568 568 new_value = g_strdup_printf ("Custom.%s", value); (gdb) print new_value $2 = (gchar *) 0x0 (gdb) n 568 new_value = g_strdup_printf ("Custom.%s", value); (gdb) n 569 gtk_cups_request_encode_option (request, key, new_value); (gdb) print new_value $3 = (gchar *) 0x7faa10914000 "Custom.Custom.595.28x841.89"
Here's confirmation obtained using gdb with evince:
Breakpoint 5, add_cups_options (key=0x7faa10a346b0 "cups-PageSize", value=0x7faa112 35a20 "Custom. 595.28x841. 89", data=0x7faa1104 1090) at /build/ buildd/ gtk+3.0- 3.4.2/. /modules/ printbackends/ cups/gtkprintba ckendcups. c:521 buildd/ gtk+3.0- 3.4.2/. /modules/ printbackends/ cups/gtkprintba ckendcups. c <optimized out>) buildd/ gtk+3.0- 3.4.2/. /modules/ printbackends/ cups/gtkprintba ckendcups. c:568 request_ encode_ option (request, key, new_value); Custom. 595.28x841. 89"
user_
521 in /build/
...
Breakpoint 6, add_cups_options (key=0x7faa10a346b5 "PageSize", value=<optimized out>, user_data=
at /build/
568 new_value = g_strdup_printf ("Custom.%s", value);
(gdb) print new_value
$2 = (gchar *) 0x0
(gdb) n
568 new_value = g_strdup_printf ("Custom.%s", value);
(gdb) n
569 gtk_cups_
(gdb) print new_value
$3 = (gchar *) 0x7faa10914000 "Custom.