Linux, b51+. Set the build as the JDK in etc/netbeans.conf, run netbeans4_2, selected some text, then do some other actions. Eventually it crashes.

Stack: [0x515e2000,0x51663000), sp=0x51662370, free space=512k
Native frames: (J=compiled Java code, j=interpreted, Vv=VM code, C=native code)
C [libc.so.6+0x621d9]
C [libc.so.6+0x625fb] __libc_free+0x8b
C [libX11.so.6+0x35fdd] XFree+0x1d
C [libmawt.so+0xd4dc] Java_sun_awt_X11_XlibWrapper_XFree+0x4c
j sun.awt.X11.XlibWrapper.XFree(J)V+0
j sun.awt.X11.UnsafeXDisposerRecord.dispose()V+215
j sun.awt.X11.WindowPropertyGetter.dispose()V+18
j sun.awt.X11.XSelection$SelectionEventHandler.dispatchEvent(Lsun/awt/X11/IXAnyEvent;)V+111
j sun.awt.X11.XToolkit.dispatchEvent(Lsun/awt/X11/IXAnyEvent;)V+144
j sun.awt.X11.XToolkit.run(Z)V+332
j sun.awt.X11.XToolkit.run()V+5
j java.lang.Thread.run()V+11
v ~StubRoutines::call_stub
V [libjvm.so+0x176e02]
V [libjvm.so+0x261458]
V [libjvm.so+0x176665]
V [libjvm.so+0x1766fe]
V [libjvm.so+0x1dd4d4]
V [libjvm.so+0x2c9c73]
V [libjvm.so+0x261f7f]
C [libpthread.so.0+0x59dd]

Java frames: (J=compiled Java code, j=interpreted, Vv=VM code)
j sun.awt.X11.XlibWrapper.XFree(J)V+0
j sun.awt.X11.UnsafeXDisposerRecord.dispose()V+215
j sun.awt.X11.WindowPropertyGetter.dispose()V+18
j sun.awt.X11.XSelection$SelectionEventHandler.dispatchEvent(Lsun/awt/X11/IXAnyEvent;)V+111
j sun.awt.X11.XToolkit.dispatchEvent(Lsun/awt/X11/IXAnyEvent;)V+144
j sun.awt.X11.XToolkit.run(Z)V+332
j sun.awt.X11.XToolkit.run()V+5
j java.lang.Thread.run()V+11
v ~StubRoutines::call_stub