ref: 9f76a7f6819ac04552b4fb6588156f3e4089d1d7
dir: /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