I've created the following page to demonstrate a problem I've had on numerous real published post and pages.
http://songbook1.wordpress.com/pp/fx/0-new-features/demo-cube-to-dodecahedron-anim/
The animated "cube to dodecahedron" image is first shown with no alignment, and transparent background. I then demonstrate that when you align the image to the right allowing text (lines sustituted, here) to wrap around it, the transparency is somehow disabled. I don't want the background, but it appears to be impossible to remove it if I use any alignment setting except "no alignment."
Blog url: http://songbook1.wordpress.com/