How can I stop windows on my mac (Mac OS Snow Leopard) from hiding when the app that owns the window loses focus.

Not all apps on the mac do this, but Photoshop and Transmission are perfect examples of apps that exhibit this behaviour.

It's frustrating when you want to type notes in another app (e.g. word processor), but refer to the contents of the window that hides when you focus the word processor to start typing your notes!

There must be an option (or hack) to disable this?

I always thought Apple were supposed to be the masters of UI design, but allowing apps to do this seems wrong.