I’ve been using Cornerstone/Pro for some time, and I’ve noticed this issue fairly persistently, but have only now been able to find a reliable trigger. Occasionally, a bug will be triggered, after which certain actions will make the editor viewport taller than the editor itself, making the page increasingly unusable until you reload the tab. I’m not sure if there are multiple triggers, but one reliable one is to load the editor at a smaller breakpoint (for example, if you’re editing on a laptop or a non-maximized browser window), and then switch to the desktop/XL/base breakpoint.
Once you’ve triggered this bug, quite a few actions will make the viewport taller, but key actions are opening the HTML editor (including when editing text or other items like the CSS editor), and resizing the Cornerstone sidebar (not the viewport–the actual sidebar). Both seem to make the viewport about 50px taller, but resizing the sidebar is much more dramatic because it seems to trigger the bug every pixel that the sidebar is resized.
I’ve been seeing this bug for several versions of Pro, and have replicated it in the following conditions:
- Different server software, including Apache, LiteSpeed, and Nginx
- Different combinations of caches in front of the server, including CloudFlare, Haproxy’s cache, LiteSpeed Cache (with and without Redis), other WordPress caching plugins, and no cache at all.
- Different browsers, including Chrome, Firefox, Edge, and Brave (in a number of different profiles and in a fresh incognito session)
- Different physical computers, on different physical networks
- Different operating systems, including Windows 10, Windows 11, and various flavors of Linux
I’ve also been able to replicate this on a number of sites, including the Cornerstone Live Demo.
I know this bug is a little hard to explain, so I’m happy to create a screen recording or share my screen to give a little more context.