We have custom property which was developed in EpiServer 5.1. This property contains user interface to do several operations on images and photo galleries. We are still showing this with the Legacy property editor, as this needs lot of effort to convert this to new DOJO widget.

The legacy editor was working fine with EpiServer 7.0. Whenever we open the property editor by clicking the "..." button beside the property name, it used to open the AJAX popup and used to resize properly, according the content width and height. But recently we have upgraded the site to 7.1.2 using "Add-On" manager. After the upgrade, the resize is not working. The property editor opens a small AJAX popup, and it does not resize to the content width and height. Also there is no option for the user to resize the popup. What could be the problem?