ADDITIONAL SYSTEM INFORMATION :
Ubuntu Linux (thus GNOME), OpenJDK 11

A DESCRIPTION OF THE PROBLEM :
I have a Swing program called Edisyn (https://github.com/eclab/edisyn) which looks great on MacOS and Windows machines even with HighDPI monitors. But on Linux it is a complete mess: the primary widgets in the GUI (JComboBoxes, JCheckBoxes, JButtons, JLabels, and certain custom-drawn widgets) do not scale with HighDPI and stay teeny-tiny. This would be fixable with an environment variable like GDK_SCALE=2, or setting -Dsun.java2d.uiScale=2.0 say. However the Menus, the JTabbedPane labels, and the widgets drawn inside JOptionPane boxes **do scale**. As a result the application is a mess of different-sized widgets, and scaling everything up just makes the already standard-sized widgets monster-sized.

STEPS TO FOLLOW TO REPRODUCE THE PROBLEM :
1. On Ubuntu OpenJDK 11, launch download and run https://cs.gmu.edu/~eclab/projects/edisyn/edisyn.jar

2. When asked, select a synthesizer from the "All Synths" combo box, and press "Open".

3. Behold

EXPECTED VERSUS ACTUAL BEHAVIOR :
EXPECTED -
All widgets would be scaled in the same way; and that way would be the standard size.
ACTUAL -
Menus, tab pane tabs, JOptionPane boxes all are "standard" sized, while everything else (both custom to Edisyn and standard in Java) are tiny.

FREQUENCY : always