Thank you for your quick reply.
Indeed the reason is configuration under Screen Saver somehow set to "Temperature and Time" instead of "All". I change it to "All", the issue is disappeared.
Hello, Only recently I got very strange display issue for Yowindow Build 88. I run it with /screenSaver mode on my primary display (a full HD LED TV). When it started it only display partial screen without top temperature panel section as if it displays bigger than the TV screen (see the attachment)...