Fix windows compilation
Fix windows compilation

Unsigned long is 32 bits on windows.

gkoz/gtk-rs-cairo,EPashkin/rust-gnome-gtk,rust-gnome/cairo,gkoz/rust-gnome-gtk,EPashkin/rust-gnome-gtk,Susurrus/gtk,EPashkin/rust-gnome-glib,gkoz/rust-gnome-cairo,drewet/gtk,insanebits/gtk,LordSentox/gtk,rust-gnome/glib,gkoz/gtk-rs-gtk,gkoz/rust-gnome-glib,Susurrus/glib,LordSentox/gtk,gkoz/gtk-rs-gtk,Susurrus/gtk,mitaa/gtk,gkoz/gtk-rs-pango,gkoz/rust-gnome-gtk,mitaa/gtk,rtsuk/cairo,daa84/gtk,insanebits/gtk,drewet/gtk,rust-gnome/gtk,daa84/gtk,gkoz/gtk-rs-glib,rust-gnome/gtk,nicokoch/glib