Vegas is designed to “play nice” with other applications. As you’ve seen, when Vegas loses focus, it will release all files so other applications can use them. This is very useful in some situations.
For example, suppose you have a photo on the timeline and you decide it needs to be modified in your photo editor. You can simply go to the photo editing program, Vegas loses focus so it will release the image, and then edit it as needed. When you go back into Vegas, it then reattaches to all files it needs including the newly modified file which will be automatically updated to the new version.
Changing the option you changed, this can no longer happen as Vegas will no longer release the files it’s using when it loses focus. However, the gain is that it doesn’t have to reattach all files once you return to Vegas.
Edward Troxel
