Popup Window With Options To Populate Textbox

Actually this is the same like the pop-up calendar but the only difference is I don't want numbers, I need a list of options so user can choose and when they select, it will transfer to the textbox right away like the calendar. I have a form and trying to use a pop-up window to select an option then transfer the option selected to show on the textbox. I have 10 textboxes and all of them has a "Select" button to pop-up the option list. BTW, the "SELECT" button will populate the same option list.

Here is my html code:
<select id="droplist" name="droplist" size="1" >
<option>Click to select...</option>
<?php foreach ($designation_list as $descode => $prompt) : ?>
<option <?php echo helper_selected($prompt == $form['droplist']); ?> value="<?php echo $prompt; ?>" style="width:500"><?php safeEcho($prompt); ?> </option>
<?php endforeach; ?>
</select>

Below is array:
<?php
$designation_list = array(
"00111" =>"Aloha of the Pacific/Transfer Assistance Program for High Income Students",
"71122" =>"Aloha",
"71231" =>"Free Housing Information",
"71232" => "Drama Queen and King",
"98765" => "Aloha Boy Home of the Land",
"12345" => "Aloha Home",
);
I wanted to use the option list over and over again for the 10 textboxes. Is that possible?

Below is my sample code but didn't work.
//javascript
var testpopup5 = new PopupWindow("testdiv5");
testpopup5.offsetX=-20;
testpopup5.offsetY=20;
testpopup5.autoHide();
var testpopup5input=null; .....
I get this code from somewhere else but it doesn't work on me.