Drag'n'Drop from TreeCtrl into other panel

Hi folks,

I've got the following problem:

I use a SplitterWindow with two panels. One Panel holds a TreeCtrl widget and
displays some options for the user to select.
The other panel should display some blocks.

I now want to drag an item of the TreeCtrl widget over to the other panel in a
special way. If i leave the TreeCtrl panel, I want to display the sorroundings
of the block in the other window.

The main problem that comes up with this is:
How can I catch MouseEvents on the panel where I want to display the blocks,
while I'm dragging over from the other panel?

I would need some kind of handover for the events when I'm leaving one panel.

Regards

Joki