fix display of error dialog when saving a gcode file to a read-only directory
fix display of error dialog when saving a gcode file to a read-only directory

thanks to cradek for catching this

kinsamanka/machinekit,yishinli/emc2,cnc-club/linuxcnc,narogon/linuxcnc,narogon/linuxcnc,ArcEye/machinekit-testing,unseenlaser/machinekit,araisrobo/machinekit,unseenlaser/linuxcnc,kinsamanka/machinekit,cnc-club/linuxcnc,unseenlaser/machinekit,cdsteinkuehler/linuxcnc,jaguarcat79/ILC-with-LinuxCNC,araisrobo/machinekit,cdsteinkuehler/linuxcnc,bobvanderlinden/machinekit,araisrobo/linuxcnc,ArcEye/machinekit-testing,bobvanderlinden/machinekit,RunningLight/machinekit,EqAfrica/machinekit,ikcalB/linuxcnc-mirror,bmwiedemann/linuxcnc-mirror,cdsteinkuehler/linuxcnc,bobvanderlinden/machinekit,RunningLight/machinekit,cdsteinkuehler/MachineKit,kinsamanka/machinekit,ianmcmahon/linuxcnc-mirror,unseenlaser/linuxcnc,RunningLight/machinekit,kinsamanka/machinekit,cnc-club/linuxcnc,Cid427/machinekit,EqAfrica/machinekit,ikcalB/linuxcnc-mirror,Cid427/machinekit,mhaberler/machinekit,unseenlaser/machinekit,bmwiedemann/linuxcnc-mirror,ArcEye/MK-Qt5,ArcEye/MK-Qt5,mhaberler/machinekit,araisrobo/machinekit,EqAfrica/machinekit,aschiffler/linuxcnc,araisrobo/machinekit,bmwiedemann/linuxcnc-mirror,cnc-club/linuxcnc,unseenlaser/linuxcnc,cnc-club/linuxcnc,EqAfrica/machinekit,Cid427/machinekit,mhaberler/machinekit,ArcEye/MK-Qt5,cdsteinkuehler/linuxcnc,bmwiedemann/linuxcnc-mirror,ianmcmahon/linuxcnc-mirror,RunningLight/machinekit,cdsteinkuehler/linuxcnc,jaguarcat79/ILC-with-LinuxCNC,jaguarcat79/ILC-with-LinuxCNC,ikcalB/linuxcnc-mirror,ianmcmahon/linuxcnc-mirror,bobvanderlinden/machinekit,mhaberler/machinekit,unseenlaser/linuxcnc,cdsteinkuehler/MachineKit,araisrobo/machinekit,ArcEye/machinekit-testing,unseenlaser/linuxcnc,RunningLight/machinekit,ikcalB/linuxcnc-mirror,strahlex/machinekit,aschiffler/linuxcnc,cnc-club/linuxcnc,aschiffler/linuxcnc,ArcEye/MK-Qt5,kinsamanka/machinekit,Cid427/machinekit,kinsamanka/machinekit,araisrobo/linuxcnc,unseenlaser/machinekit,araisrobo/linuxcnc,bmwiedemann/linuxcnc-mirror,araisrobo/machinekit,araisrobo/linuxcnc,Cid427/machinekit,EqAfrica/machinekit,ikcalB/linuxcnc-mirror,unseenlaser/machinekit,RunningLight/machinekit,strahlex/machinekit,strahlex/machinekit,ArcEye/MK-Qt5,yishinli/emc2,strahlex/machinekit,araisrobo/machinekit,ikcalB/linuxcnc-mirror,Cid427/machinekit,cdsteinkuehler/MachineKit,Cid427/machinekit,unseenlaser/machinekit,mhaberler/machinekit,bmwiedemann/linuxcnc-mirror,ArcEye/MK-Qt5,EqAfrica/machinekit,strahlex/machinekit,cnc-club/linuxcnc,cdsteinkuehler/MachineKit,araisrobo/machinekit,narogon/linuxcnc,bobvanderlinden/machinekit,ianmcmahon/linuxcnc-mirror,ArcEye/machinekit-testing,ArcEye/machinekit-testing,cdsteinkuehler/MachineKit,cdsteinkuehler/linuxcnc,yishinli/emc2,araisrobo/linuxcnc,ianmcmahon/linuxcnc-mirror,ianmcmahon/linuxcnc-mirror,kinsamanka/machinekit,ianmcmahon/linuxcnc-mirror,strahlex/machinekit,Cid427/machinekit,narogon/linuxcnc,strahlex/machinekit,mhaberler/machinekit,kinsamanka/machinekit,jaguarcat79/ILC-with-LinuxCNC,ikcalB/linuxcnc-mirror,bobvanderlinden/machinekit,cdsteinkuehler/MachineKit,aschiffler/linuxcnc,bobvanderlinden/machinekit,RunningLight/machinekit,EqAfrica/machinekit,mhaberler/machinekit,bmwiedemann/linuxcnc-mirror,unseenlaser/machinekit,jaguarcat79/ILC-with-LinuxCNC,ArcEye/MK-Qt5,bobvanderlinden/machinekit,RunningLight/machinekit,narogon/linuxcnc,mhaberler/machinekit,unseenlaser/machinekit,ArcEye/machinekit-testing,aschiffler/linuxcnc,ArcEye/MK-Qt5,ArcEye/machinekit-testing,yishinli/emc2,ArcEye/machinekit-testing,EqAfrica/machinekit,araisrobo/machinekit