I was busy in the scripteditor...
Selected to scripting documentation from the options menu...
Switched back (alt-tab) to the scripting editor...
When I moved my mouse over the options button again, it changed to the default Windows style of buttons...
(it looked normally before my mouse was over it. Other buttons stayed in Plus! style).
See actual screenshot.
Not reproduceable...
Plus! 4.01.240, Windows XP Home SP2 5.1.2600