The window is still a radiator. Or more accurately, will still radiate heat received from a warmer source toward a colder destination.
Heat tends towards dispersal (currently predicted, eventually, to evenly spread in all directions), so it seems wrong to say that the window "attracts" heat. Rather, it just provides lower resistance to heat transfer than the typical wall.
While the feeling may be similar to a draft (moving air), the actual phenomenon is radiant heat transfer. The warmth we feel is not just air temperature (which can be less than half), but also the surface temperatures:
* https://en.wikipedia.org/wiki/Mean_radiant_temperature
* http://www.healthyheating.com/Definitions/Mean%20Radiant.htm
If you sit near a heating radiator, fireplace, or campfire, you will feel warm because energy goes from high concentration (fire) to low/er concentration (your body).
But if you sit near a badly insulating window, your body has the higher amount of energy (heat) so energy goes from you to the window. You are the radiator for the window; the window is an 'anti-radiator' (it 'attracts' heat).