1.5 is not blocking popups. At first I thought it was something I might of been doing wrong and realized I was not. I tested this with FF and noticed it did not get the popup and showed the window at the top of the browser saying it had blocked a popup.
I have noticed on many sites when there is a popup and you click on the site, click on text to highlight and copy, click on an image, anything you can think of that requires you to click someone on a website causes a popup to appear.
All I can tell you is that this is extremely annoying, and I hope will be fixed in the next version.
Here is the post I made about this in the General section:
http://kmeleonbrowser.org/forum/read.php?1,82457
THANKS