24
Try giving the form a name.
For example :
<script type="text/javascript">
script>
<form name="info">
<input type="text" name="number" size="20">
<input type="button" onClick="popup()" value="Go!">
form>
If you have a file named 1.html in your XOOPS root directory, then if you type '1' in the textbox, it should popup in the window.
Make sure you save the custom block as HTML.
The code is working for me so I'm not sure what the problem is...