Is there a way to list assets for which a selected user (not the current user) has got write access?
No -- Matrix always checks permissions against the current user. You can specify what level of permission to check, though.
What I wanted to do was list a set of assets that a particular user has created and has write access to so that an administrator can manage those in the context of who had created them. I guess the only way to do this would be to link the asset under that particular user's workspace (using a customer trigger action) and to asset list based on the selected user.
You want to reduce the number of links an asset has, as this will reduce the overall number of rows in your link table, which improves performance. Can you not use a single asset listing group by the asset attribute of %asset_attribute_created%* which should list the username of the person who created the page?
- Note: I am not near a Matrix system, so please check this keyword. It is used for example purposes only.
In general that approach worked, except that some assets are created by a telemarketing agent on behalf of a third party. In this case the telemarketer creates a user for the 3rd party, creates some assets and then 'allocates' those assets by setting write access. Now they want to list the assets that have been 'allocated' to the 3rd party.
Not sure if you can do this via Simple Edit, but you can change the user who "created" an asset on the Settings screen of the asset itself.
I've checked but cannot find a field to set the 'created by' for an asset anywhere on the settings screen.
If you have Admin permission to an asset, on the Settings screen you can change the Date/User for both the Created and Last Published values. The Last Published remains dynamic though (as Matrix will overwrite that every time the asset is made Live).
The options are under the "Dates" heading -- you get to change the date, and there is an asset picker for the "By" field.