newbie ? on Flip

On the example below was wondering why I get a flip
count only when I move the mouse, I can wait 20 seconds
move the mose barely and the count increments by 10
obviously due to the mod 10 statment. My question is
if I make no mouse movement isn't the main code still
continuously looping ? Thanks,

-------------------------------------------------------

'This function will be automatically called every Flip
Function MyHook:Object( id,data:Object,context:Object )
Global count

count:+1
If count Mod 10=0 Print "Flips="+count

End Function

'Add our hook to the system
AddHook FlipHook,MyHook

'Some simple graphics
Graphics 640,480,0

While Not KeyHit( KEY_ESCAPE )

Cls
DrawText MouseX()+","+MouseY(),0,0
Flip

Wend

I would wager that blitz max decides not to flip if it detects no change to the backbuffer.