Client Side Decoration (CSD) Windows seem bigger to panels, so they auto-hide with no need

- MX Linux 19.3 (Debian 10 Buster)
- XFCE 4.14
- GTK 3.24.5

If a non-CSD window is almost touching an intelli-hiding panel, it will not hide until the window overlap it, however, if the window is being CSD, so the panel will hide even when the window is too away from the panel to touch it.

I know this is panels-related, but I don't know how much related to any XFCE-subproject because I can replicate this behavior with the Plank panel too.

You can test it with the XFCE Terminal (non-CSD) and Tilix (CSD), or toggling the Firefox's [ ] Title Bar feature in the Customize page.

Here is a video demonstration:

https://youtu.be/5MwDkECInWA