Fix a crash in the loupe tool
Fix a crash in the loupe tool

Double clicking on the loupe tool caused the crash

https://bugzilla.gnome.org/show_bug.cgi?id=669354

mans0954/f-spot,mans0954/f-spot,dkoeb/f-spot,dkoeb/f-spot,Yetangitu/f-spot,dkoeb/f-spot,mans0954/f-spot,mans0954/f-spot,Sanva/f-spot,Sanva/f-spot,mono/f-spot,dkoeb/f-spot,mono/f-spot,Yetangitu/f-spot,GNOME/f-spot,dkoeb/f-spot,Yetangitu/f-spot,Sanva/f-spot,Sanva/f-spot,NguyenMatthieu/f-spot,NguyenMatthieu/f-spot,Yetangitu/f-spot,mono/f-spot,mono/f-spot,mono/f-spot,GNOME/f-spot,NguyenMatthieu/f-spot,NguyenMatthieu/f-spot,GNOME/f-spot,Sanva/f-spot,dkoeb/f-spot,GNOME/f-spot,mans0954/f-spot,mans0954/f-spot,Yetangitu/f-spot,GNOME/f-spot,NguyenMatthieu/f-spot,mono/f-spot