check canvas is not null before access prev focus
check canvas is not null before access prev focus

barmalei/zebra,barmalei/zebkit,barmalei/zebkit,gigakiller/zebra,msudol/zebra,msudol/zebra,gigakiller/zebra,olemis/zebra,msudol/zebra,satishgoda/zebra,gigakiller/zebra,olemis/zebra,satishgoda/zebra,olemis/zebra,barmalei/zebra,satishgoda/zebra