ref: 60ecd07e6d3f5786c8723dc9172c35d580fdadc8
dir: purgatorio/libtk/radio.tk
radiobutton .u -text {Upper case} -variable case -value u
radiobutton .l -text {Lower case} -variable case -value l
radiobutton .i -text {Ignore case} -variable case -value i
pack .u .l .i -anchor w -fill x