Descriptive Problem Summary:
There seems to be a problem with selecting transparent background colors and interfaces not rendering properly.

Numbered Steps to Reproduce Problem:
Set an image for a label with some transparency.
Set the background color of the label to a color.
Set the transparent color of the window to the same color.

At this time you can show/hide the interface element to reproduce, or you can open the window in the interface editor and sometimes it will not render there either. You can toggle the check mark for the transparency option in the interface editor and it will correct the issue at hand.

Does the problem occur:
Every time? Or how often?
It does not happen every time. It is seemingly random.
In other games?
Unknown, I'd assume so?
In other user accounts?
Yes.
On other computers?
No. This does not happen on my windows 8.1 desktop. This does happen on my Windows 7 64bit laptop. It also happens on a friends Windows 7 64 bit machine.

When does the problem NOT occur?
It seems to only never happen on my windows 8.1 desktop.

This problem happens with the latest Beta and the latest Stable.

Workarounds:
Toggling the transparency check-box seems to fix the rendering. However once the window is hidden or you close the window in the interface editor it will randomly screw up again.

I've also made a post about the issue here: http://www.byond.com/forum/?post=1715421

I'm having a hard time reproducing this as well. It seems to be a hit and miss with people. I can send Tom or Lummox a copy of the project with issues if needed.

If the issue is present, you should be able to see the issue just by viewing the interface in the editor. You'll just have to close and open it a few times.