set ns [new Simulator]
set tcp [new Agent/TCP]
$tcp set window_ 1

# This fails!
puts [$tcp window]
# So does this:
#puts [$tcp window_]

(_o10 cmd line 1)
    invoked from within
"_o10 cmd window"
    invoked from within
"catch "$self cmd $args" ret"
    invoked from within
"if [catch "$self cmd $args" ret] {
set cls [$self info class]
global errorInfo
set savedInfo $errorInfo
error "error when calling class $cls: $args" $..."
    (procedure "_o10" line 2)
    (SplitObject unknown line 2)
    invoked from within
"$tcp window"
    invoked from within
"puts [$tcp window]"
    (file "window-test.tcl" line 8)

puts [$tcp set window_]