2 clicks on the editable DIV or INPUT type=text placed over the Flash movie disables the typing, no matter the Flash wmode, no matter the position of the IFRAME and Flash movie (absolute, relative, fixed). Changing the focus restores the typing.
DIV with contenteditable="true", placed over the Flash movie. Click here, type to edit. Click again, can't type anymore, but the keydown event stil fires with keyCode=0 (see Firebug console)
DIV with contenteditable="true", not placed over the Flash movie. Click here, type to edit. Click again, can type.