Tabbed windows & door

[N. W. Perry]

Ah, perfect. I've found exactly the image I needed:
https://flic.kr/p/rxWHUM

This shows me several things:

• The window is the same width as a brick
  
• The tabs lie flush to the back side of the window
  
• The tab does not fill the entire slot, but in fact is about half as thick
  
• An example of each of three ways the tabs are used:
  

1. In a slot
   
2. Behind a neighboring brick (the curved macaroni brick here)
   
3. In front of a neighboring brick, but behind a round 1x1 brick)
   

Options 1 and 2 appear to work without distorting the window (aside from the ubiquitous warping of all cellulose acetate parts that we can see), so our geometry should reflect that. Option 3 is clearly a kludge, albeit an official one, so we should not try to accommodate that.

Rough measurements from that photo show that the tab is actually about 3 LDU thick (the slot is 4), which doesn't really make geometric sense, so I've settled on a 2 LDU tab.

Here is my revision of the u8012 door, along with an updated version of the tab. Pending any discussion here, I'll submit these as fixes to the existing parts as I create them.

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EDIT:
Wow, things worked out even better than I expected! By having a 2 LDU-thick tab, and by moving the window forward by 2, you can indeed fit in front of a neighboring brick, but behind a round 1x1, while also fitting within the slots. See what I mean:
   

So all of the official "connections" for these parts can in fact be made, without any collisions or having to physically bend anything.