ref: 61870c24fae357b78029ce54be0c004e1ffdb3c7
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