What is causing the edges of my models to become semi-transparent? All of a sudden, in a particular scene I am working on, the edges of all the models have become partially transparent.  It is like what happens when you have a very small start clipping pane and are looking at a small model up close.  Except the clipping panes have not been changed, most of the objects in the scene are not very small, and I am not zoomed way in.

Here is a screenshot:


The crude barn thing pictured in the screenshot is about 30'x25'x26' and the zoom is pretty standard.  This behavior is also not dependent on the zoom, and again, I have not changed the clipping panes.

And I do have limit selection to visible checked, it does look similar to what it would if that was disabled, but that is not the problem.

What is this caused by and technically what is responsible for it?
What you are seeing is directly related with the value on the clip start distance. 



Bring up the value a bit and the effect will go away.



Seems like setting the start clip distance to anything smaller than 0.1 (or 10cm if using metric)  will bring that weird transparency.