Window.Open Does a Cache? How to direct URL to a parent?

I have a page with multiple grids. Clicking on the main grid should navigate to a new webpage. I use code like this to do it:

var RowChg = function(){window.open("ChgData.wc?Source=Drawer&ID=" + this.getProperty("selection/index"), "_parent")}

This works fine EXCEPT (there's always an except isn't there?), it appears to cache the pages once it has them and display the old cache.

Navigating to the page above should fire code on my server to update the secondary grids. I can see the address line change in the browser but the server code never actually fires. This makes me think a cached page is being displayed instead of actually navigating to that page.

If I put links on the page to the same thing, that works. I've set Expire Immediately to be on for my website.

Any ideas why a cached page is being shown?
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Or, I could change that function to something like:
var RowChg = function(){document.location.href = "http://www.paladinpgm.com/default.htm?ID=" + this.getProperty("selection/index")}

But my grid is in an iframe. How do you change that line of code to add in the "target = _parent"?

Server cache see this post
http://www.activewidgets.com/messages/509-2.htm

No, that's not it. I had found that post and set the IIS server to Expire the pages immediately. That fixed a problem with the grid never picking up the changed data source but it hasn't solved this problem.

I click the grid which does a window.open but it doesn't actually fire the server to run code. It seems to be using a cached page.

If I close the browser and reopen, everything works until I try to display the same page twice.

I would add a random dummy param to URL to resolve this.

var RowChg = function(){var myRand = (new Date).getTime(); window.open("ChgData.wc?Source=Drawer&ID=" + this.getProperty("selection/index") + "&rand=" + myRand, "_parent")};

Didn't test it, so there can be some typo. But you got the idea ?

Cheers,
Sudhaker Raj