Error when adding nodes

[landwirt@…]

What steps will reproduce the problem?

1. Start JOSM
2. Open or create a new map layer
3. Choose Draw mode and click into the layer to add a node

What is the expected result?
A node is added and a line is drawn between node and mouse cursor.

What happens instead?
I get the error message below.

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

The last working build is 4220, with 4223 I get the same error.

Repository Root: http://josm.openstreetmap.de/svn
Build-Date: 2011-07-16 01:31:39
Last Changed Author: stoecker
Revision: 4250
Repository UUID: 0c6e7542-c601-0410-84e7-c038aed88b3b
URL: http://josm.openstreetmap.de/svn/trunk
Last Changed Date: 2011-07-15 21:52:06 +0200 (Fri, 15 Jul 2011)
Last Changed Rev: 4250

Identification: JOSM/1.5 (4250 en)
Memory Usage: 1472 MB / 1472 MB (1340 MB allocated, but free)
Java version: 1.6.0_22, Sun Microsystems Inc., Java HotSpot(TM) 64-Bit Server VM
Operating system: Windows 7
Dataset consistency test: No problems found

Plugin: DirectUpload (26284)
Plugin: buildings_tools (26254)
Plugin: contourmerge (25626)
Plugin: editgpx (26284)
Plugin: openvisible (26174)
Plugin: plastic_laf (26174)
Plugin: reverter (26254)
Plugin: terracer (26174)
Plugin: turnrestrictions (26174)
Plugin: utilsplugin2 (26320)

java.lang.AbstractMethodError
	at org.openstreetmap.josm.data.osm.event.PrimitivesAddedEvent.fire(PrimitivesAddedEvent.java:25)
	at org.openstreetmap.josm.data.osm.DataSet.fireEventToListeners(DataSet.java:942)
	at org.openstreetmap.josm.data.osm.DataSet.endUpdate(DataSet.java:921)
	at org.openstreetmap.josm.data.osm.DataSet.addPrimitive(DataSet.java:346)
	at org.openstreetmap.josm.command.AddCommand.executeCommand(AddCommand.java:50)
	at org.openstreetmap.josm.command.SequenceCommand.executeCommand(SequenceCommand.java:53)
	at org.openstreetmap.josm.data.UndoRedoHandler.addNoRedraw(UndoRedoHandler.java:36)
	at org.openstreetmap.josm.data.UndoRedoHandler.add(UndoRedoHandl

[stoecker]

Closed as duplicate of #6596.