Any small amount of convexity along the grey border will cause an example to fit right.
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precise, allsorted, unwordable, notso, perfect
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Leo Crabbe
https://en.wikipedia.org/wiki/Opaque_set
Adjacent-numbered pages: BP1244 BP1245 BP1246 BP1247 BP1248  *  BP1250 BP1251 BP1252 BP1253 BP1254
notso, blackwhite, right-null, perfect, bordercontent