How can I close an empty pane in Eclipse

Question

I often end up with lots of empty panes in Eclipse that can only be minimized but not destroyed. How do I close these?

Update:

In this screenshot you can see two minimized on the upper left and several on the right hand side. In the center are four more. They only seem to be restorable in the Debug mode.

http://img406.imageshack.us/img406/9900/eclipse1.png

Answer 1

this happened to me, too. What worked for me (based on FilmJ and douncon's comments) was to open a class file, then drag that tab over the top of the empty pane.