DnD operation can freeze Xserver. It's appeared on Linux/Gnome, Solaris, w2k with jdk1.4 (jdk1.4.0-build92). This combination freezes Xserver sure:
1. a modal dialog as drag source
2. another component (e.g. JList in JFrame)
3. the modal dialog is show in SwinUtilities.invokeLater
4. the cursor enters in a component during DnD
==> Xserver freezes.

See attached test, try run DnDFreezesTest on jdk1.3_03 --> w/o problems
try run it on jdk1.4-b92 --> described behavior!

Thanks for attention.