The Preferences window is not visible on Windows Taskbar, meaning that when
its hidden beneath other windows Processing seems locked up. The tough one
is if it gets hidden under the editor window, as they then lock each other.
(Happens for example if you open preferences and double click Processing
task on the taskbar.)

Not a biggie, but might confuse user with the result of killed process and
lost work due to neglect of regular saves.

k, i think this is just a java issue with JFrames, but we'll have to find a
way to work around it.