Background window not grayed out when a modal window is open on Linux/Gnome

[Zlika]

I repost this bug from eclipse-platform/eclipse.platform.swt#1416 because I don't know if it's a SWT or platform.ui problem. Sorry for that.

Describe the bug
When a modal dialog box is open, the default behavior under Gnome is to gray out the background window. This was the (expected) behavior on old versions of the Eclipse IDE (up to Eclipse 4.4/SWT 3.103). However, more recent versions of Eclipse/SWT (starting from Eclipse 4.5/SWT 3.104 up to the latest version) seem to change this behavior, and the background is no longer grayed out when a modal dialog is open.

To Reproduce
Open a recent version Eclipse under Linux/Gnome and open the "About Eclipse" modal dialog: the background is not grayed out.

Expected behavior
The background should be grayed out when a modal dialog box is open to be consistent with the Gnome look'n feel.

Screenshots
"About Eclipse" dialog box with Eclipse 4.4:

"About Eclipse" dialog box with Eclipse 4.5:

Environment:

1. Select the platform(s) on which the behavior is seen:

• • All OS
• • Windows
• • Linux
• • macOS

2. Additional OS info (e.g. OS version, Linux Desktop, etc)
   Debian 12.6 with Gnome Desktop

3. JRE/JDK version
   Any.

Version since
Eclipse or SWT version since when the behavior is seen: Eclipse 4.5 / SWT 3.104.

Workaround (or) Additional context
I would love to know if a workaround exists.