Now it seems that the Color Picker in the latest RSD 1.5 Build 1366 likes to move around.
Open RSD.
Go to Design set a color. The Color Picker is in pretty much the center of the program.
http://www.decalsandtees.com/misc/rsd/Snapshot_1.png
Click OK.
Go to set a color again and the Color Picker is now at the bottom right of the program and has to be moved up manually.

http://www.decalsandtees.com/misc/rsd/Snapshot_2.png

Thanks for reporting that. This issue has been addressed for the next release.

How can I get RSD beta 1366?

Build 1350 is the latest build.