invalid command name "toplevel"
    while executing
"toplevel .form"
    (procedure "LabelTextDemo_2" line 2)
    invoked from within
"LabelTextDemo_2"
    (in namespace eval "::request" script line 225)
    invoked from within
"namespace eval ::request $script"
    ("::try" body line 12)
OUTPUT BUFFER:
#!/usr/local/bin/wish

############################################
#
# LabelText.tcl
# ------------------------
#
# Copyright (C) 2005 William J Giddings
# email: giddings@freeuk.com
#
############################################
#
# Description:
# -----------
# Provide mutliline entry widget.
#
# Args:
# ----
#
# base         the full pathname of the megawidget.
# args
#
# returns	     returns the pathname of megawidget created
#
# Accessing Label and Text Components:
# -----------------------------------
#
# Note:
# ----
# The name of the variable associated witht the text widget is
# integrated into the name of the ** TEXT ELEMENT ** of the megawidet.
# If there are any changes to the variable, or text, a trace is called
# and the name of the variable is then used to modify the content of the
# associated widget.
#
# The assumption made is that this widget will be primarily used as a
# form centred multi-line entry widget rather than a text editing box.
# Under such cases, a textvariable should always be used.
#
# Ensure that textvariable exists prior to creations of the widget.
#
# Caveats:
# -------
# This widget has only been tested using array variables in the global
# namespace, consequently, some issues may arise if a custom
# namespace is used.
#
# The widget is effectively "hard-coded" to a particular textvariable.
# Whilst this is the expected case for most uses of the widget, some code
# modification would be required to enable the change of tectvariable to be
# reflected in the full pathanme of the text element itself.
#
# Should any change be made then perhaps the existing text element needs
# to be replaced with one in which the textvariable name included in the pathname.
# Following this, all bindings and traces need to be unset for the old textvariable
# and new bindings and traces set for the new tracevariable.
#
# No effort has been made to trace array calls to the textvariable.
#
############################################
proc LabelText {base {args {}}} {
    #set default values
    set frargs  ""
    set txtargs ""
    set labargs ""
    set txtpack ""
    set labpack ""
    #parse arguments, assign to label/text components
    foreach {arg val} $args {
	switch -- $arg {
	    -relief {append frargs " $arg $val " }
	    -borderwidth {append frargs " $arg $val " }
	    -labelfont {append labargs "-font \{$val\} " }
	    -labelwidth {append labargs " -width $val "}
	    -labelheight {append labargs " -height $val "}
	    -labeltext	{append labargs " -text \{$val\} "}
	    -labeljustify {append labargs " -justify $val "}
	    -labeltextanchor {append labargs " -anchor $val "}
	    -labelbg -
	    -labelbackground {append labargs " -background $val "}
	    -labelfg -
	    -labelforeground {append labargs " -foreground $val "}
	    -labeltextvariable {append labargs " -textvariable $val" }
	    -labelside {
		append labpack " -side $val "
		append txtpack " -side $val "
	    }
	    -labelanchor {
		append labpack " -anchor $val "
		append txtpack " -anchor $val "
	    }
	    -width -
	    -height -
	    -background -
	    -foregroung -
	    -bg -
	    -fg -
	    -font {append txtargs " $arg \{$val\} "}
	    -textvariable {
                #todo: Create variable if one does not exist
		set variable $val
                set a $variable
                puts $a
		trace var ::$a wu _$a
                set ::${a}_ $base.$variable
                ###################################################
                #create bespoke trace handler
                ###################################################
                proc _$a {name i op} {
		    # args passed to the fucntion
		    # name	variable name
		    # i    array index
		    # op   operation
		    #upvar 1 $name var
                    if {$::DEBUG} {
                        puts ">> name: $name i: $i op: $op"
                        #puts "[set ::${name}(${i})_]"
                    }
		    
                    #deal with unset variables
                    if { $op == "u" } {
                        if { $i != {} } {
                            rename _$name {}
                        } else {
                            rename _${name}(${i}) {}
                        }
                        return
                    }
                    #assuming variable to be an array, ie $i != NULL
                    if {$i != {} } {
                        #variable is and array
                        [set ::${name}(${i})_] delete 1.0 end
                        [set ::${name}(${i})_] insert end [set ::${name}(${i})]
                    } else {
                        #simple variable
                        [set ::${name}_] delete 1.0 end
                        [set ::${name}_] insert end [set ::${name}]
                    }
                } 
		#end proc
	    } 
	    # end textvariable block
	} 
	#end switch
    } 
    #end foreach
    # build megawidget
    frame $base {*}$frargs
    label $base.lab {*}$labargs
    pack $base.lab {*}$labpack
    text $base.$variable {*}$txtargs
    pack $base.$variable {*}$txtpack -in $base
    if {$::DEBUG} {
	bind "$base.$variable"  {
	    # get variable name
	    set tmp %W
	    puts "%W -- [winfo parent %W]"
	    puts "%W -- [winfo pathname [winfo id %W]]"
	    puts [lindex  [split %W .] end]
	}
    }
    #update variable when focus is lost
    bind "$base.$variable"  {
	set a [%W get 1.0 end]
	set b [lindex  [split %W .] end]
	#if {$::DEBUG} { puts "a = $a b = $b \n[set $b]" }
	#remove any blank lines
	set $b [string trimright [string trimleft $a]]
    }
    #return location
    return $base
}
################################################################################
# Demo Block
################################################################################
set ::DEBUG true
proc LabelTextDemo_1 {{base {}} } {
    if {$::DEBUG} { catch {console show} }
    LabelText $base.lt1 \
	    -relief raised \
	    -borderwidth 2 \
	    -labeltext "Prime Minister's\nAddress" \
	    -labelanchor nw \
	    -labeltextanchor nw \
	    -labelside left \
	    -labelwidth 15 \
	    -labeltextvariable var1 \
	    -labeljustify left \
	    -textvariable pm_address \
	    -background #ffffdd \
	    -width 20 \
	    -height 7 \
	    -istitle 1
    pack $base.lt1 -fill both -expand 1
    LabelText $base.lt2 \
	    -relief raised \
	    -borderwidth 2 \
	    -labeltext "Chancellor's\nAddress" \
	    -labelanchor nw \
	    -labeltextanchor nw \
	    -labelside left \
	    -labelwidth 15 \
	    -labeltextvariable var2 \
	    -labeljustify left \
	    -textvariable ce(address) \
	    -width 20 \
	    -height 7 \
	    -istitle 1
    pack $base.lt2 -fill both -expand 1
}
proc LabelTextDemo_2 {} {
    toplevel .form
    wm title .form "LabelText Demo"
    LabelTextDemo_1 .form
    pack [button .b1 -text "Tony Blair" -command {set ::pm_address "10 Downing St.,\nLONDON"}] -fill x
    pack [button .b2 -text "Gordon Brown" -command {set ::ce(address) "11 Downing St.,\nLONDON"}] -fill x
    pack [button .b3 -text "puts pm_address" -command {puts $pm_address } ] -fill x
    pack [button .b4 -text "puts ce(address)" -command {puts $ce(address) } ] -fill x
    pack [button .b5 -text "unset pm_address" -command {unset pm_address } ] -fill x
    pack [button .b6 -text "unset ce(address)" -command {unset ce(address) } ] -fill x
    
    set ::ce(address) "11 Downing St.,\nLONDON"
    set ::pm_address "10 Downing St.,\nLONDON"
}
LabelTextDemo_2