http://code.google.com/p/pharo/issues/detail?id=1236 Tested with OBSystemBrowserAdaptor in pharo1.0-10451-BETAdev09.09.3 on Windows. To reproduce: 1) Open a System Browser 2) Create a new class. When you do this, when you are changing "#NameOfSubclass" to "#YourClass", after doing this press the down arrow key 3) An empty pop up will be brought and the keyboard won't respond. To fix this, you must press "Esc" key. Best, Mariano