Recover properly when quad_stack.viewport_ is unset
Recover properly when quad_stack.viewport_ is unset

git-svn-id: 3a56fcae908c7e16d23cb53443ea4795ac387cf2@569 0e6d7f2b-9903-5b78-7403-59d27f066143

bpsinc-native/src_third_party_trace-viewer,bpsinc-native/src_third_party_trace-viewer,bpsinc-native/src_third_party_trace-viewer,bpsinc-native/src_third_party_trace-viewer