Do you mean Popup windows or banner ads? Both can be blocked in K-meleon. They are in mine. For Popup Windows control go to
Edit-Preferences-Privacy-Popup Control or you can create a
toolbar button through macros to block or allow them.
For Banner Ads, using a hosts file works very well for me. It blocks banner ads from all browsers and html mail without having to tweak each browser's or mail apps settings and connections.
Click here to visit a website which explains how to do it and has the hosts file. It's not hard.