Comment 3 for bug 39206

The valgrind output is a lot more informative:

==26286==
==26286== Invalid free() / delete / delete[]
==26286== at 0x401CFCF: free (vg_replace_malloc.c:235)
==26286== by 0x4732E8B: g_free (gmem.c:187)
==26286== by 0x81385B4: gimp_dockable_destroy (gimpdockable.c:245)
==26286== by 0x46DF422: g_cclosure_marshal_VOID__VOID (gmarshal.c:77)
==26286== by 0x46D316E: ??? (gclosure.c:567)
==26286== by 0x46D379E: g_closure_invoke (gclosure.c:490)
==26286== by 0x46E2B16: ??? (gsignal.c:2554)
==26286== by 0x46E3B18: g_signal_emit_valist (gsignal.c:2197)
==26286== by 0x46E3E88: g_signal_emit (gsignal.c:2241)
==26286== by 0x42771F1: ??? (gtkobject.c:419)
==26286== by 0x434289E: ??? (gtkwidget.c:6672)
==26286== by 0x46D5EAB: g_object_unref (gobject.c:1734)
==26286== Address 0x5261718 is 0 bytes inside a block of size 7 free'd
==26286== at 0x401CFCF: free (vg_replace_malloc.c:235)
==26286== by 0x4732E8B: g_free (gmem.c:187)
==26286== by 0x81385D6: gimp_dockable_destroy (gimpdockable.c:251)
==26286== by 0x46DF422: g_cclosure_marshal_VOID__VOID (gmarshal.c:77)
==26286== by 0x46D316E: ??? (gclosure.c:567)
==26286== by 0x46D379E: g_closure_invoke (gclosure.c:490)
==26286== by 0x46E2B16: ??? (gsignal.c:2554)
==26286== by 0x46E3B18: g_signal_emit_valist (gsignal.c:2197)
==26286== by 0x46E3E88: g_signal_emit (gsignal.c:2241)
==26286== by 0x42771F1: ??? (gtkobject.c:419)
==26286== by 0x434289E: ??? (gtkwidget.c:6672)
==26286== by 0x46D69F3: g_object_run_dispose (gobject.c:571)