screenshot now displays a helpful error message when it fails
screenshot now displays a helpful error message when it fails

now that larger xinerama setups are getting more common, it's also the case that shm creation is more likely to fail due to SHMMAX defaults only working on displays smaller than than 8,388,609 total pixels. in this case, we print a helpful error message so the user can (optionally) increase SHMMAX

tizenorg/platform.upstream.enlightenment,rvandegrift/e,tasn/enlightenment,FlorentRevest/Enlightenment,tizenorg/platform.upstream.enlightenment,tasn/enlightenment,rvandegrift/e,tasn/enlightenment,FlorentRevest/Enlightenment,rvandegrift/e,tizenorg/platform.upstream.enlightenment,FlorentRevest/Enlightenment