ThinWire Ajax RIA Framework

I get the following error message occasionally when attempting to open a
tree (clicking on the (+) expansion. The problem only happens once in a
while, and I can not reproduce it consistently. The tree nodes are
configured to recieve drag/drop events, but other than that, there is
nothing special about the tree being used.

java.lang.IllegalArgumentException: sourceComponentX{-2} < 0
at thinwire.ui.event.DropEvent.<init>(DropEvent.java:73)
at thinwire.ui.event.DropEvent.<init>(DropEvent.java:65)
at
thinwire.render.web.ComponentRenderer.componentChange(ComponentRenderer.jav
a:353)
at
thinwire.render.web.TreeRenderer.componentChange(TreeRenderer.java:153)
at
thinwire.render.web.WebApplication.captureThread(WebApplication.java:958)
at
thinwire.ui.AbstractWindow.setWaitForWindow(AbstractWindow.java:110)
at
thinwire.render.web.WebApplication$3.run(WebApplication.java:337)