invalid command name "frame"
    while executing
"frame .f"
    (in namespace eval "::request" script line 11)
    invoked from within
"namespace eval ::request $script"
    ("::try" body line 12)
OUTPUT BUFFER:
#!/usr/local/bin/wish

proc newfb {} {
    foreach e [winfo children .f.b] {
	destroy $e
    }
    text .f.b.t -width 10
    pack .f.b.t
}

frame .f
pack .f -side top -expand 1 -fill both
grid rowconfig .f 0 -weight 0 -minsize 0
grid columnconfig .f 0 -weight 0 -minsize 0
frame .f.a
frame .f.b
grid .f.a -row 0 -column 0
grid .f.b -row 1 -column 0

button .f.a.bt -text "delete" -command [list newfb]
grid .f.a.bt -row 0 -column 0 -sticky w

for {set i 0} {$i < 4} {incr i} {
    for {set j 0} {$j < 4} {incr j} {
	button .f.b.bt${i}${j} -text "bt $i $j"
	grid .f.b.bt${i}${j} -row $i -column $j
    }
}