signal_key_press_event() doesn't work for spacebar

[Jellyworld <me jia-han com>]

When i use the signal_key_press_event() function to add a listener to my 
window class, the resulting function gets called when i press any key 
except the space keys (ie spacebar, enter, tab).  Why is this so?  Is 
there any way to add get notified when i press the spacebar?