If by your own code you mean "direct GTK calls to build ui", then I would switch to it for several reasons:
- if widgets are built dynamically depending on user settings, etc.
- if I use a lot of custom widgets, especially. (e.g. GDL docking panels).
- GTK
upd: glade2.x, ( gtk2). "gui build from code" , GTK. , gtk3:)
gtkbuilder , (- ) GTK. dunno, - . , gtk3.