java.awt.AWTError: BoxLayout can't be shared

[kolesar]

What steps will reproduce the problem?

1. Create a new layer (Ctrl+N)
2. Draw a way with 3 nodes.
3. Create a new relation, make new way as a member, save relation.
4. Split the way at the middle point.
5. Combine the two ways.

Attached .osm file with steps 1-4 ready. You only need to combine the two ways to reproduce bug.

What is the expected result?

Ways to be combined.

What happens instead?

Exception: java.awt.AWTError: BoxLayout can't be shared

Please provide any additional information below. Attach a screenshot if possible.

Used latest .jar file downloaded from website. Tested version does not have this bug. Started JOSM with empty preferences, no plugins.

URL:http://josm.openstreetmap.de/svn/trunk
Repository:UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
Last:Changed Date: 2016-01-20 01:28:07 +0100 (Wed, 20 Jan 2016)
Build-Date:2016-01-20 02:32:45
Revision:9547
Relative:URL: ^/trunk

Identification: JOSM/1.5 (9547 hu) Linux Ubuntu 15.10
Memory Usage: 281 MB / 672 MB (91 MB allocated, but free)
Java version: 1.8.0_66-b17, Oracle Corporation, Java HotSpot(TM) Server VM
Dataset consistency test: No problems found


Last errors/warnings:
- E: java.awt.AWTError: BoxLayout can't be shared

java.awt.AWTError: BoxLayout can't be shared
	at javax.swing.BoxLayout.checkContainer(BoxLayout.java:465)
	at javax.swing.BoxLayout.invalidateLayout(BoxLayout.java:249)
	at javax.swing.BoxLayout.addLayoutComponent(BoxLayout.java:282)
	at java.awt.Container.addImpl(Container.java:1127)
	at java.awt.Container.add(Container.java:417)
	at org.openstreetmap.josm.gui.conflict.tags.RelationMemberConflictResolver.build(RelationMemberConflictResolver.java:67)
	at org.openstreetmap.josm.gui.conflict.tags.RelationMemberConflictResolver.<init>(RelationMemberConflictResolver.java:120)
	at org.openstreetmap.josm.gui.conflict.tags.CombinePrimitiveResolverDialog.buildRelationMemberConflictResolverPanel(CombinePrimitiveResolverDialog.java:185)
	at org.openstreetmap.josm.gui.conflict.tags.CombinePrimitiveResolverDialog.build(CombinePrimitiveResolverDialog.java:173)
	at org.openstreetmap.josm.gui.conflict.tags.CombinePrimitiveResolverDialog.<init>(CombinePrimitiveResolverDialog.java:221)
	at org.openstreetmap.josm.gui.conflict.tags.CombinePrimitiveResolverDialog$1.run(CombinePrimitiveResolverDialog.java:102)
	at org.openstreetmap.josm.gui.util.GuiHelper.runInEDTAndWait(GuiHelper.java:110)
	at org.openstreetmap.josm.gui.conflict.tags.CombinePrimitiveResolverDialog.getInstance(CombinePrimitiveResolverDialog.java:100)
	at org.openstreetmap.josm.gui.conflict.tags.CombinePrimitiveResolverDialog.launchIfNecessary(CombinePrimitiveResolverDialog.java:504)
	at org.openstreetmap.josm.actions.CombineWayAction.combineWaysWorker(CombineWayAction.java:183)
	at org.openstreetmap.josm.actions.CombineWayAction.actionPerformed(CombineWayAction.java:222)
	at javax.swing.SwingUtilities.notifyAction(SwingUtilities.java:1663)
	at javax.swing.JComponent.processKeyBinding(JComponent.java:2882)
	at javax.swing.KeyboardManager.fireBinding(KeyboardManager.java:307)
	at javax.swing.KeyboardManager.fireKeyboardAction(KeyboardManager.java:263)
	at javax.swing.JComponent.processKeyBindingsForAllComponents(JComponent.java:2974)
	at javax.swing.JComponent.processKeyBindings(JComponent.java:2966)
	at javax.swing.JComponent.processKeyEvent(JComponent.java:2845)
	at java.awt.Component.processEvent(Component.java:6312)
	at java.awt.Container.processEvent(Container.java:2236)
	at java.awt.Component.dispatchEventImpl(Component.java:4891)
	at java.awt.Container.dispatchEventImpl(Container.java:2294)
	at java.awt.Component.dispatchEvent(Component.java:4713)
	at java.awt.KeyboardFocusManager.redispatchEvent(KeyboardFocusManager.java:1954)
	at java.awt.DefaultKeyboardFocusManager.dispatchKeyEvent(DefaultKeyboardFocusManager.java:806)
	at java.awt.DefaultKeyboardFocusManager.preDispatchKeyEvent(DefaultKeyboardFocusManager.java:1074)
	at java.awt.DefaultKeyboardFocusManager.typeAheadAssertions(DefaultKeyboardFocusManager.java:945)
	at java.awt.DefaultKeyboardFocusManager.dispatchEvent(DefaultKeyboardFocusManager.java:771)
	at java.awt.Component.dispatchEventImpl(Component.java:4762)
	at java.awt.Container.dispatchEventImpl(Container.java:2294)
	at java.awt.Window.dispatchEventImpl(Window.java:2750)
	at java.awt.Component.dispatchEvent(Component.java:4713)
	at java.awt.EventQueue.dispatchEventImpl(EventQueue.java:758)
	at java.awt.EventQueue.access$500(EventQueue.java:97)
	at java.awt.EventQueue$3.run(EventQueue.java:709)
	at java.awt.EventQueue$3.run(EventQueue.java:703)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:86)
	at java.awt.EventQueue$4.run(EventQueue.java:731)
	at java.awt.EventQueue$4.run(EventQueue.java:729)
	at java.security.AccessController.doPrivileged(Native Method)
	at java.security.ProtectionDomain$JavaSecurityAccessImpl.doIntersectionPrivilege(ProtectionDomain.java:76)
	at java.awt.EventQueue.dispatchEvent(EventQueue.java:728)
	at java.awt.EventDispatchThread.pumpOneEventForFilters(EventDispatchThread.java:201)
	at java.awt.EventDispatchThread.pumpEventsForFilter(EventDispatchThread.java:116)
	at java.awt.EventDispatchThread.pumpEventsForHierarchy(EventDispatchThread.java:105)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:101)
	at java.awt.EventDispatchThread.pumpEvents(EventDispatchThread.java:93)
	at java.awt.EventDispatchThread.run(EventDispatchThread.java:82)

[kolesar]

Closed as duplicate of #12405.
Update: relation not needed. Combining ways is enough. Duplicate of #12405 that was submitted while I was typing this ticket.