JVM crashes when JOptionPane is displayed from the drop() method. When the drop occurs, the JOptionPane is displayed, but the JVM crashes after that. This happens only when the JOptionPane is displayed before the dropComplete() method is called. Please see the bug 4623377. The testcase attached is the same one given in the description of that bug. Please see the log also attached.

The crash is not consistent. It occurs on Solaris and Linux only with MToolkit. I was able to reproduce the problem in both the OS in 2-3 drag & drops.

Steps to reproduce:
1. Run the attached code.
2. Drag a node from the tree and drop it on the tree itself.
3. Repeat it 2-3 times and it can be seen that the JVM crashes.