Summary

Control window appearance by a new client property in AWT on macOS.

Problem

Rich client applications (IntelliJ IDEA for example) need control over window appearance to align decorations with the application themes. Please note, the existing JVM option "apple.awt.application.appearance" does not cover the need for dynamic changing of the window appearance.

Solution

Extend the macOS AWT by a string client property corresponding to the attribute "appearance" of native windows. The new client property is applied to the root panes of windows.

Specification

The new property follows the format of some existing properties (See CPlatformWindow.java for a complete list):

"apple.awt.windowAppearance"

The string property can be initialized by any name of the existing appearance supported by macOS. Here is the list https://developer.apple.com/documentation/appkit/nsappearancename?language=objc

For example:

rootPane.putClientProperty("apple.awt.windowAppearance", "NSAppearanceNameVibrantDark")