Coldfusion 2018 update 2 broke CFWindow center="true"

I spent a couple days struggling with this and felt I needed to share with the community.

I've been running CF 2018 locally for a while, but the production server (internal website only) was CF 11. I was pretty confident that I had addressed all the version differences because I'd been using it locally, so I finally got my ducks in a row to purchase the upgrade for production and rolled it out this week. Shortly after deploying the new server, users started complaining about popup windows not working correctly. We had a handful of CFWindow tags that were modal="true" and center="true". When the user clicked the link that called ColdFusion.Window.show('windowname') the screen would go grey (modal) but the window was not popping up cented in the viewable area, sometimes ending up off the bottom of the page (esp. when viewed on mobile devices), and they thought their web page had locked up.

After a day and a half of flailing, I determined the underlying issue and backtracked to find that Update 2 https://helpx.adobe.com/coldfusion/kb/coldfusion-2018-update-2.html (which I applied immediately to the new production server when I built it, but only applied locally in the last couple of weeks) had done this:

• Updated the following OEMs:
  • ExtJS 6.6.0.258 for AJAX UI components

The CFWindow tag is tied to this ExtJS library, and the update changed the way it works. I don't know specifically what changed or why it was broken, but my solution was to replace the whole library with the previous version (4.x). 

The next step for me will be to rewrite all the old code to replace the cfwindow tags with something else, but this was my quick fix.

Hopefully this post helps someone else and keeps them from googling in vain for days like I did.