User Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:56.0) Gecko/20100101 Firefox/56.0 Build ID: 20171002220106 Steps to reproduce: Install "Selection Context Search" and click its button from the menu. This works fine in Firefox 56 and 55. Actual results: The "default_popup" will be displayed, but it will be shrunk vertically. Because of this, its content will not be visible. The content of the popup should be some text and a button. Expected results: The entire content of the popup should be shown correctly.
Please contact the extension author to get help.
I am the author of the add-on. The add-on popup window shows collapsed vertically in 57beta without changing anything to it.