It is experienced on jdk1.4.x for Windows only (on jdk1.3 for Windows it seems to be fine).
1) Doing DnD, i.e. dragging component in application on windows using jdk1.4.x, above drop targets and outside drop target borders, occasionally freezes the app. During that time CPU is 100% used, app gives no responses, it takes usually about 5 sec, but were experienced cases up to 82 seconds.
2) On Netbeans it is possible to experience this issue very often, probably it has something to do with the amount of events run in the app. But event on testcase, which is comparing to NB trivial no event handling is done, it is possible to experience the problem. Note: it is experienced neither on jdk for Linux nor Solaris.
3) Testcase. It is possible to experience too. But you have to be more patient.
a) Repeat quickly to drag the component from tree, it seems to, you have to do quick motions, and go also outside the panel, provide the drop to the right area. Do more attempts in the row, sometime above the 10 are necessary to get the problem.
b) Sometimes you get the problematic state, it was experienced on windows jdk1.4.0-fcs, and 1.4.1-b08, but it wasn't on jdk1.3.1_03.
c) The problem is on NB it is seen much more easier, thus making the feature not usable.