canvas oval outlinestipple

canvas .c -bg white -width 200 -height 200; pack .c -expand yes -fill both
.c create rect 100 0 200 200 -fill yellow -width 0
.c create oval 50 50 150 150 -outlinestipple gray12 -outline blue -width 50

# result:  https://imgur.com/a/BDX1C