the first example I explained how the focus was the issue, between the textArea and the button.
now you post code that contains a couple of textfields, and presumably, your problem happens when you follow these steps type something into the textArea type something into the find textfield (possibly) type something into the replace textfield click the find button
now the textArea doesn't show the selection - is that the problem?
if so, where is the focus now? not the button - that was a fix for the first posted code. could the focus be with the last textfield that something was typed into?
anyway, look up the apidocs for textArea.requestFocusInWindow();