Fixed a minor compilation issue against Gtk# 2.7.1
Fixed a minor compilation issue against Gtk# 2.7.1

    * src/GtkSharpBackports/FileChooserButton.cs: Fixed a minor compilation
    issue against Gtk# 2.7.1

directhex/banshee-hacks,eeejay/banshee,dufoli/banshee,petejohanson/banshee,lamalex/Banshee,mono-soc-2011/banshee,Dynalon/banshee-osx,directhex/banshee-hacks,dufoli/banshee,ixfalia/banshee,lamalex/Banshee,stsundermann/banshee,arfbtwn/banshee,arfbtwn/banshee,ixfalia/banshee,petejohanson/banshee,lamalex/Banshee,mono-soc-2011/banshee,GNOME/banshee,arfbtwn/banshee,lamalex/Banshee,directhex/banshee-hacks,petejohanson/banshee,GNOME/banshee,allquixotic/banshee-gst-sharp-work,Carbenium/banshee,stsundermann/banshee,arfbtwn/banshee,allquixotic/banshee-gst-sharp-work,Carbenium/banshee,mono-soc-2011/banshee,dufoli/banshee,Carbenium/banshee,arfbtwn/banshee,GNOME/banshee,babycaseny/banshee,babycaseny/banshee,Dynalon/banshee-osx,ixfalia/banshee,babycaseny/banshee,stsundermann/banshee,directhex/banshee-hacks,stsundermann/banshee,Dynalon/banshee-osx,babycaseny/banshee,lamalex/Banshee,mono-soc-2011/banshee,arfbtwn/banshee,dufoli/banshee,Dynalon/banshee-osx,lamalex/Banshee,allquixotic/banshee-gst-sharp-work,Dynalon/banshee-osx,GNOME/banshee,GNOME/banshee,petejohanson/banshee,mono-soc-2011/banshee,stsundermann/banshee,dufoli/banshee,Dynalon/banshee-osx,GNOME/banshee,Carbenium/banshee,petejohanson/banshee,Carbenium/banshee,eeejay/banshee,babycaseny/banshee,arfbtwn/banshee,allquixotic/banshee-gst-sharp-work,allquixotic/banshee-gst-sharp-work,ixfalia/banshee,ixfalia/banshee,eeejay/banshee,ixfalia/banshee,babycaseny/banshee,Carbenium/banshee,stsundermann/banshee,allquixotic/banshee-gst-sharp-work,stsundermann/banshee,eeejay/banshee,ixfalia/banshee,GNOME/banshee,arfbtwn/banshee,mono-soc-2011/banshee,mono-soc-2011/banshee,babycaseny/banshee,directhex/banshee-hacks,dufoli/banshee,petejohanson/banshee,eeejay/banshee,dufoli/banshee,babycaseny/banshee,directhex/banshee-hacks,GNOME/banshee,dufoli/banshee,Dynalon/banshee-osx,Dynalon/banshee-osx,ixfalia/banshee,stsundermann/banshee