I can't reproduce that problem - the OS open dialog remains visible as I switch applications, and I'm able to drag files and folders into the dialog from the Finder.
Also, there is no reason I can think of why the OS open dialog would disappear until you commit or cancel it.
1) Open Photoshop CS6
2) Open an existing file by double clicking it or opening with dialog)
3) Select File > Open, and click on the Desktop
The Open dialog does not vanish?
This is Mac only. Never tried it in Windows.
The OS open dialog stays visible, no problems.
It sounds like you may have something wonky on your system.
I think I figured it out.
The open/save is not disappearing, it is moving behind my already open document (making it equally useless). Also, I had the Application Frame active. If the Application Frame is inactive then it works fine.
OK, so somehow the OS is changing the window order when it probably shouldn't be - especially when you're using an application that goes full screen (aka the annoying application frame).
Yup. That appears to be it - only when the application frame is active. Pretty crazy. Thanks for your help.