Ejemplo de la operacion "element closest" en BLT

Fuente: https://www.tek-tips.com/viewthread.cfm?qid=503800
Adaptado para RBC.

package require rbc

rbc::vector create x(20)
rbc::vector create y(20)

x seq 1 20
y random

rbc::graph .g
pack .g -expand yes -fill both

.g element create data -xdata x -ydata y

toplevel .report -bg black
label .report.info -textvariable status -justify left -bg yellow
pack .report.info -padx 2 -pady 2

wm withdraw .report
wm overrideredirect .report 1

.g element bind data {
    if {[.g element closest %x %y click]} {
        set status "Clicked on \"$click(name)\" element\n"
        append status "Data point $click(index)\n"
        append status "x value: $click(x), y value $click(y)"
       
        wm geometry .report +%X+%Y
        wm deiconify .report
    }
}

.g element bind data {
    wm withdraw .report
}