FULL PRODUCT VERSION :
JDK 8u261 b12

ADDITIONAL OS VERSION INFORMATION :
MS Windows 10 OS

A DESCRIPTION OF THE PROBLEM :
The user's application sets a window size by the method "javax.swing.JFrame.setSize(Dimension)", but starting from JDK 8u261 this method breaks the layout of the UI components in the window of the user's application. The issue is demonstrated on the attached screenshot "Screenshot.jpg".

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. Compile and run the attached test case "PMJframe.java".