Dialog parent can be a closed window

[rkeen-siemens]

Apache NetBeans version

Apache NetBeans 26

What happened

Utilities.findDialogParent can return a non-visible component which is effectively equivalent to null and will cause issues similar to #4739 and #5987.

Language / Project Type / NetBeans Component

No response

How to reproduce

Run the following code on the EDT:

DialogDescriptor first = new DialogDescriptor("Parent is the main window", "First");
DialogDisplayer.getDefault().notify(first);

DialogDescriptor second = new DialogDescriptor("Parent is first's dialog", "Second");
DialogDisplayer.getDefault().notify(second);

The first dialog will have the main window as the parent, but the second will have the dialog created for first even though it has been closed.

Did this work correctly in an earlier version?

No / Don't know

Operating System

Linux

JDK

21.0.5

Apache NetBeans packaging

Apache NetBeans platform

Anything else

Here's what seems to be happening:

1. Closing the first dialog submits a WINDOW_CLOSED event to the event queue
2. Before the event is processed, notify opens the second dialog
3. This end up in DialogDisplayerImpl.AWTQuery.showDialog() which ultimately gets the new dialog’s parent using org.openide.util.Utilities.findDialogParent
4. This returns the active window from KeyboardFocusManager.getCurrentKeyboardFocusManager().getActiveWindow() which is still the now closed first dialog because the WINDOW_CLOSED event hasn’t yet been processed

Updating Utilities.findDialogParent to resolve a suggested parent via the closed window's owner would probably resolve the issue. Something like this after the modal check may work:

if (parent instanceof Window w) {
    while (!w.isVisible()) {
        w = w.getOwner();
        if (w == null) {
            break;
        }
    }
    parent = w;
}

Are you willing to submit a pull request?

No

[neilcsmith-net]

That seems somewhat like a JDK bug, but PR welcome.

As a workaround, does using setLeaf(true) help? Or run the second dialog via EventQueue::invokeLater?

[mbien]

reminds me on #6772

[neilcsmith-net]

@mbien yes, and curious what the behaviour of that was prior to #5989 Happy if @rkeen-siemens wants to fix his original fix, but needs something with a reproducer that can be properly tested across OS. I still have scars from the last look at this! 😄

Unfortunately, I think the JDK behaviour is somewhat broken. The desire to make Dialog synchronous and the secondary EDT just has too many quirks like this for my liking. I often find myself using dialogs via invokeLater to ensure events have run through. Curious if the bug is also reproducible with https://bits.netbeans.org/26/javadoc/org-openide-dialogs/org/openide/DialogDisplayer.html#notifyFuture(T) That might be a better API for combining dialogs.