Not a bug
BYOND Version:479
Operating System:Windows 7 Home Premium 64-bit
Web Browser:Firefox 3.6.13
Applies to:Dream Seeker
Status: Not a bug

This is not a bug. It may be an incorrect use of syntax or a limitation in the software. For further discussion on the matter, please consult the BYOND forums.
Code should explain/demonstrate the problem:
stat("Click Your Name Below")
stat("Move the mouse off your name, but still inside the stat panel")
stat("Start to type in the input (it should still have focus)")
stat("The mouse cursor should disappear")
stat("It will reappear if you move it out of the stat panel")
stat("similar problems exist in general over other controls as well")

world<<input("Input:","Input") as text
Have you verified the windows setting "Hide my cursor while I type" is also not turned on?
All I see is the cursor disappearing while typing, which I confirmed is a Windows setting (it's in mouse controls).