I generally upload appropriately optimized PNG's with transparency (see recent media upload "A bad day for the black swan"). I set my pictures so that clicking them opens the actual file. I do this because in the past, when a person clicked on the file, it opened on a black background which defined my collages' irregular edges.
Something has changed somewhere because now, when I click an image in a post, it opens on the black background, but the transparency becomes white.
It looks horrible.
This has changed in the past few weeks...
I have also noticed that the default action when clicking on my media images USED to open the file itself. Now, it opens the picture in a stripped-out post page. Is there somewhere to change the default action when images are clicked?