How do you propose that works?
Exactly like Adobe Illustrator. If you're familiar, a placed object in illustrator that hasn't been embedded, will automatically update if the original artwork has changed (even if the content was changed by another program). If the illustrator file containing the linked artwork is open when a change is made to the linked artwork, you get a popup on reentering illustrator asking if you would like to commit the changes.
I realize it's a complex feature, but it would be a monumental upgrade to Photoshop Smart Objects.
If the placed psd is updated, naturally all documents containing that psd would be updated to reflect the changes.
I also think i may have worded this poorly... obviously Photoshop cant force other programs to update their own open files, or anything like that. I was just trying to reiterate the fact that if a Photoshop Smart Object could be linked to an external psd... and that external file was changed, all other psd's with that linked file would reflect the changes when opened, or previewed.
OK, its a fair request. And its one I'm sure they are very carefully looking at. It does have problems based on the same fundamental limitation that stops the much requested Auto-save feature being implemented.
Photoshop files can be enormous. Indesgn and Illustrator are vector based apps. When you link to an external file in these apps, any time reading off the disk is a lot more minimal than it would be in Photoshop.
To explain one of the the problems, take this scenario: You have a Photoshop file with 20 linked Smart Object documents. You, or someone who's wife you had an entertaining night with last night, then chooses to upsample the linked documents by 500%. You then try and open the master document. What happens? Your carefully worked Photoshop file is now more or less unopenable. Just freezes, while it goes through the automatic process of trying to read in twenty 4 Gig files. The solution is to have an Update all documents command of some sort of course. But the external linking behaviour that Illustrator shows cannot be directly copied satisfactorily .
As a near term solution, have a look here:
There's a CS4 and a CS5 version, plus it looks like Mike Hale has provided the Flex project for further customization if you're so inclined.
This doesn't preclude investigations to make your feature request more robust and included as part of a shipping Ps version.
SG, great link. Something I wasn't aware of.
Mike Hale's Links Panel works, with a few minor glitches. He updated it with an "Update All" button if you look later in the thread.
The advantage with this over "Replace Contents", which I assume the OP is aware of by the way, is that it records the path to the external file, and also allows opening of the linked file from within the panel.