[Natch]

1] Your original code is

PHP Code:

<a href="#" onclick="showthread.php?$session[sessionurl]do=testaction&amp;t=$threadid; return false;">Execute Test Action</a> 


Should be

PHP Code:

<a href="#" target="windowname" onclick="showthread.php?$session[sessionurl]do=testaction&amp;t=$threadid; return false;">Execute Test Action</a> 


^^ That would work, but it's not really ideal as you have no control over the structure or "features" of the window...

2] OK: the structure of the window.open() function is as follows...

window.open(this.href,this.target,"toolbar=yes, location=yes, directories=no, status=no, menubar=yes, scrollbars=yes, resizable=no, copyhistory=yes, width=400, height=400")

There was an omitted set of Quotes in my code above around the final argument of the function...

The structure can be broken down into three arguments: link URI, window name (same as target), and features.

Link can be either a quoted URI (eg "forumdisplay.php?f=1342") or a legal DOM reference (aka this.href refers to the contents of the href statement in this a tag... ).

Window Name similarly can be either a quoted value for the window name (eg "_blank", "mypopup") or a legal DOM reference (aka this.target refers to the target field in this a tag... ).

This example above uses the extended version of the code for features, the only features that require a name=value structure are width and height, the others you only need to include a feature name if you wish it to be active.

So: your code should be

PHP Code:

<a href="showthread.php?$session[sessionurl]do=testaction&amp;t=$threadid" target="threadpop" onclick="window.open(this.href,this.target,'width=400,height=400,resize'); return false;">Execute Test Action</a> 


The reason this is a really ideal way of creating your popup links is that it will degrade well if users have JS turned off, in that a new window will still open, due to the target value being a real name, if it's blank, then it opens in this window...

Final Note:

A funky implementation or this is in the following example...

PHP Code:

<tr><td id="approach" class="row1" onmouseover="changeSty('row1hi',this.id)" onmouseout="changeSty('row1',this.id)" onclick="navCMPS(this.firstChild.href)"><a href="/somelink.php">a Linkage</a></td></tr> 


This is a part of a Navigation menu, and the two JS functions called are either changing the style onmouseover the Table Cell, or causing a link/popup to be called onclick of the Table Cell, without requiring much alteration for each new line... the opnly two changes reuquired are the link and name, and the link ID should be unique for each link...

HTH