use strict;
use Tk::Balloon;

my $b = $toplevel_wg->Balloon(-statusbar=>$toplevel_wg);
$b->attach($toplevel_wg,
               -balloonmsg => "I am on the smaller window",
               -statusmsg => "Status bar message");
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$att_res = $balloon->attach($balloon, -balloonmsg => "toplevel entry b
+ox balloon/tooltip",
                            ^^^^^^^^  -statusmsg  => "toplevel entry b
+ox status");
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Also, it is not necessary to create multiple balloons unless the attributes (other than -(balloon|status)msg) differ. One balloon widget can be attached to many other widgets, each having a different -(balloon|status)msg.

I have used the suggestions and corrections and all now works as I wanted it to.
Therefore many thanks for pointing me in the right direction.
Below is the Perl for this which now includes a button which brings up the secondary window so that the ‘balloon’ can be tested.


use strict "vars";
use Tk;
use Tk;
use Tk::TabFrame;
use Tk::Balloon;
my ($a_tbfr, $tab_mw, $b_tbfr, $frame_wg);
my ($lb_str, $en_str, %tabwg, $tabwg_item, $current_product, $gen_str,
+ $j, $j_str, %wg, $wg_item, $att_res);
my ($msgarea, $balloon_msg, $status_msg, $bl_str);
my ($button_sc, $toplevel_entry_wg, $toplevel_wg, $balloon); 
$current_product = 'unset';
$tab_mw = MainWindow->new;
$tab_mw->Label(-text => 'Tabbed Frame to Check Tooltips')->grid(-row =
+> 0);
# create the tabbed frame
$a_tbfr = $tab_mw->TabFrame
(
    -font =>'-adobe-times-medium-r-bold--14',
    -tabcurve =>4,
    -padx => 10,
    -pady => 10,
    -width => 400
);
# add button that gives additional screen with button
$button_sc = $tab_mw->Button(
    -text => 'See top level widget',
    -command => sub
    {
        $toplevel_wg->deiconify();
        $toplevel_wg->raise();
    })
  ->grid(-row => 2);
# create the message area for tooltips
$msgarea = $tab_mw->Label(-borderwidth => 2, -relief => 'groove')
  ->grid(-row => 3);
# create a ballon for this message area etc
$balloon = $tab_mw->Balloon(-statusbar => $msgarea);
# create the tabbed frames each with a label and entry box
$a_tbfr->grid ('-row' => 1);
for($j = 1; $j <= 3; $j ++) {
    $j_str = "Tab " . $j;
    $tabwg{$j_str} = $a_tbfr->Frame
    (
        -caption => $j_str,
    );
    $lb_str = "Tab " . $j . '_Label';
    $wg{$lb_str} = $tabwg{$j_str}->Label(-text => "Text in Label in $j
+_str",
                      -width => 50)->grid(-row => 2, -column=>0);
    $en_str = "Tab " . $j . '_Entry';
    $wg{$en_str} = $tabwg{$j_str}->Entry (-text => $en_str,
                      -width => 20)->grid(-row => 3, -column=>0);
    $balloon_msg = "Tab " . $j . " balloon / tooltips message";
    $status_msg  = "Tab " . $j . " status message";
    $att_res = $balloon->attach($wg{$en_str}, -balloonmsg => $balloon_
+msg,
                            -statusmsg  => $status_msg);
    print "attach result <$att_res> for widget <$en_str>\n";
}

# create a TopLevel widget
$toplevel_wg = $tab_mw->Toplevel();
# create an entry box for this toplevel widget
$toplevel_wg->Label(-text => "Text above entry box")->grid(-row => 0);
$toplevel_entry_wg = $toplevel_wg->Entry(-width => 20)->grid(-row => 1
+, -column=>0);
$toplevel_wg->Label(-text => "Text below entry box")->grid(-row => 2);
# withdraw the second toplevel widget
$toplevel_wg->withdraw();
$att_res = $balloon->attach($toplevel_entry_wg, -balloonmsg => "toplev
+el entry box balloon/tooltip",
                                -statusmsg  => "toplevel entry box sta
+tus");
print "attach result <$att_res> forwidget <top_level_entry>\n";
MainLoop;
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