If I switch those two lines as you mentioned:

create_tk_window();#this was after the next line
threads->new(\&update_thread)->detach;
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It appears to work to some extent, but after a while, yuo get errors. However i tried twice, and got different message each time. Once it said:

update_thread called...
Free to wrong pool 223f40 not 1bcf528 at C:/Perl/site/lib/Tk.pm line 4
+06.
Attempt to free unreferenced scalar: SV 0x1e7643c at C:/Perl/site/lib/
+Tk.pm line
 247.
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That was the same error you mentioned that you saw. But the second time, I saw a different message (but the program does not fail for a long time, I killed it at the end):

Attempt to free non-existent shared string '_TK_RESULT_' at C:/Perl/si
+te/lib/Tk.
pm line 247.
Attempt to free non-existent shared string '_TK_RESULT_' at C:/Perl/si
+te/lib/Tk.
pm line 247.
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