What do you think where the problem is? Are you following a C example or the Krause book?
As you know I am using only GTK3 -- but from my memory of examples and the Krause book I think that the second parameter of gtk_image_new_from_stock is generally a C enum of type GtkIconSize. So allowed values may be 0,1,2... and the absolute size value 32 may be invalid. Well just a guess, I have not the gtk2 sources or the gtk2 nim wrapper available currently. For your last question, the number (5319) is the process id, so it contains no information of error location. GTK developers generally compile whole GTK (and maybe other libs too) with debugger support, and then seems to be able to find error locations with gdb. I tried that once to find the reason for a gtk warning, but was not really successful. Generally it is easier to write just correct code, so you need no low level debugging.
