steps to reproduced:
1 Load the unsigned applet inside the browser: http://sqeweb.us.oracle.com/deployment1/deployment_6_UR_int_exec_ws/6/deployment/src/javafx/fxfeaturesTest/fxfeaturesTest/html/FullscreenTextTest.html
2 Type something inside the text area within the primary stage running inside the browser.
3 Make sure that all keyboard input is read by an applet
4 Click button "Toggle Fullscreen" to go to full screen mode inside the primary stage within the browser
5 Try to send Spacebar to text area. If Full screen window can not respond to Spacebar, then the bug reproduced.

Note: Full screen window can respond to Shift, Ctrl, Alt, Enter/Return, Tab,Up, Down, Left, Right arrows