Hrm, why arent you using regexes? I'm no master, but I think this will help:
m|\*\*(\w+)\b|g If you have all the text in a scalar, you can do this:

while($text =~ m|\*\*(\w+)\b|g) {
    print "Found: " , $1 , "\n";
}
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Is this what you want? Or was there some reason you're using TK's functions??

HTH

Update: explanation of regex

m|
 \*     #literal asterisk
 \*     #ditto
 (      #start capture
 \w+    #one or more word characters aka [A-Za-z0-9_]
 )      #end capture
 \b     #word boundary
|gx     #/x allows whitespace, /g makes it global (restart from last m
+atch position in this case)
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In case you're not familar with regexes, run this: perldoc perlretut :)

mhoward - at - hattmoward.org