okay, this is how I'd actually lay it out :)

#!/usr/bin/env tclsh

package require Tk

proc entry_insert {entry_name value} {
    $entry_name configure -state normal
    $entry_name delete 0 end
    $entry_name insert end $value
    $entry_name configure -state readonly -readonlybackground white
}

panedwindow .pw -orient horizontal

labelframe .pw.x1 -text Bapy
label .pw.x1.l1 -text "L1" -justify left
entry .pw.x1.e1 -width 48 -justify right
entry_insert .pw.x1.e1 "AAAAAAAAAA"

# The marvelous wonders of RELATIVE PLACEMENT are not really
# on display here because there's only one row, hmm...
grid .pw.x1.l1 .pw.x1.e1 -sticky ew
grid columnconfigure .pw.x1 1 -weight 1

labelframe .pw.x2 -text Mojo
label .pw.x2.l1 -text "L2" -justify left
entry .pw.x2.e1 -width 48 -justify right
entry_insert .pw.x2.e1 "AAAAAAAAAA"

grid .pw.x2.l1 .pw.x2.e1 -sticky ew
grid columnconfigure .pw.x2 1 -weight 1

.pw add .pw.x1
.pw add .pw.x2

grid .pw -sticky nsew
grid rowconfigure . 0 -weight 1
grid columnconfigure . 0 -weight 1