threads->yield();

##</code><code>##

saveThreadContext;
restoreThreadContext;

##</code><code>##

#######my $DataQueue = Thread::Queue->new();
...
#wait for data, print data to GUI textbox
#######while(Win32::GUI::DoEvents() != -1) {
#######    my $tmptxt = $DataQueue->dequeue();
#######    $main_text_window->Append($tmptxt);
#######}

Win32::GUI::Dialog();

sub mainloop {
    while (1) {
        #lots of page getting and number crunching goes here
##########        $DataQueue->enqueue("some data");
        $main_text_window->Append($tmptxt);
    }
}