Launch your other Tk programs with a fork and exec:

# simplest way, but ignores error handing
my $pid;
if($pid = fork() == 0)
    {                                                       
      exec("other_tk_script");
    }
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Also, you can store those $pids in the main Tk script, so you can kill -9 them, if they hang, or you want to close them all together simultaneously.

Here is a preferred syntax

#!/usr/bin/perl
my $kidpid;

if ( !defined( $kidpid = fork() ) ) {
    #fork returned undef, so failed
    die "Cannot fork: $!";
}
elsif ( $kidpid == 0 ) {
    # fork returned 0, so this branch is child
    exec("xterm -e top");
    # if exec fails, fall through to the next statement
    die "can't exec : $!";
}
else {

    # fork returned 0 nor undef
    # so this branch is parent
    sleep(5);
    my $result = kill "TERM", $kidpid;
    print "Killed child process $kidpid (result $result)\n";
    sleep(5);

}
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