I had the opposite problem a while back. I had a text field in which the tab key entered \t when I wanted it to shift focus. Simply using bind didn't work. Here is what I wound up doing:

my $t1 = $mw->Text(
         -background=>"navy",
         -foreground=>"white",
         -height=>35,
         -width=>80,
         -wrap=>"word",
         -selectbackground=>"blueviolet"
         );
$t1->bindtags( [ ($t1->bindtags)[1,0,2,3] ] );                        
+    # fix the bindtags order so that widget events are
                                                                      
+   # processed before class events
$t1->bind("<Tab>", sub { $t1->focusNext; Tk->break; });               
+   #Fix tab to shift focus, not print a tab.
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Perhaps something similar is what you need.