14.04.1 LTS, Trusty Tahr
OpenGL vendor string: Advanced Micro Devices, Inc.
OpenGL renderer string: AMD Radeon HD 5700 Series
OpenGL version string: 4.3.12798 Compatibility Profile Context 14.10.1006.1001
Broken: Blender 2.73 (sub 1) build commit date: 2014-12-31 23:50 c24b694
Possibly also Blender 2.72, but not Blender 2.69?
Short description of error
Tranparency rendering problems in the 3D viewport. I was running a custom built 2.72 from several weeks ago, and I was having trouble with transparency that wasn't a problem in the stock Ubuntu 2.69 package. When I saw that there was a recent commit related to this, I downloaded and built 2.73 to see if it fixed the issue. It did not.
I've attached a file which hopefully demonstrates the problem. It's simply a solid cube inside another cube, with the inner cube having an opaque materials and outer cube material set for alpha blend transparency (green glass). Sometimes it renders as expected, and sometimes it does not. The incorrect result is that the inner object does not show through the transparent glass outer object, even when the background does. If you remove one face of the outer cube, the effect is more obvious, with part of inner cube being rendered, and part of it not (as if the outer cube were opaque even though it isn't. The problem is intermittent, and too random for me to be able to recreate reliably, so interpret the remaining statements as impressions.
Things that I have observed causing problems (or sometimes fixing problems):
Changing render engines. Changing shading modes in the 3D viewport. Selecting and deselecting objects in the outliner or 3D viewport. Switching from GLSL to multitexture and back.
Sometimes the problem persists in the Blender Render engine, when switching from the Blender Game engine, but it usually goes away (and stays away for a while).
My apologies if I'm doing something wrong. I'm still trying to learn how to use blender, and this is all very confusing to me. I've reported it as a bug because of it's randomness and the changes in behavior across multiple recent versions of blender.