Tried to install DockerToolbox-1.8.2 on my MacBook Pro (running OS X10.8) last night.
But the DockerToolbox installer kept hanging. Googled around a bit. Tried a number of suggestions from various forums. None worked. Finally I noticed that most of the other users having this problem were also using OS X 10.8.
So, on a whim, I decided to update my Mac to Yosemite (OS X 10.10.5 to be specific). And that fixed the problem. I am now happilly running Docker on my MacBook Pro.
Over the next week or two, I'm sure to discover some apps that no longer work, probably while in the middle of a presentation. But at least docker works!