Thank you for your response !
Versions are mentioned in the first message :
Yed 3.19 - java 11.0.2 - Windows 10 64 bits
1. I have made supplementary tests, and problem is probably linked with multi screen usage and a windows setting : my laptop screen have a Settings-System-Display-Scale and Layout-set to 125 % and other screen no scaling. (1920 x 1080 - Extended view)
2. It is effectively the same problem.