On Solaris:

If you copy data into the clipboard (using the clipboard API's),
select text in a text field and hit Ctrl-C the text currently
in the clipboard will replace (Paste) the selected text

If you copy data in text areas (never touch the Clipboard class)
Ctrl-C copies

I am including a simple test case (see attachments)
To duplicate the problem:
Run the test program
* click over the drawn text ("this is a test")
(this places the text in the clipboard)
* type data in to the text field (above the drawn text)
* select some or all of the data in the text field
         * hit Ctrl-C
"this is a test" will replace the selected data