The existing hooks: post open, post close, post clone (patch submitted), are insufficient in the tab clone case where users employ custom tab parameters. Such tab parameters often need post-clone curation. In my case, cumbersome tab-bar advice is needed to work around cloning. Others might experience the same need.

I see a few ways we can help address this. Once we agree on an approach, I'm happy to submit a patch.

1. Alter tab-bar-tab-post-open-functions to accept an optional second argument, namely, the originating tab, iff tab-bar-new-tab-choice 'clone.

2. Create a new hook tab-bar-post-duplicate-tab-functions, the functions of which accept two arguments: the originating tab, the cloned tab, and where the hook runs iff tab-bar-new-tab-choice 'clone.

3. In harmony with clone-frame, tab-bar could propagate tab parameters to a cloned tab (it already saves them naturally, for use in undo close tab), modulo internal tab-bar parameters. A post-clone hook would still be needed to allow a user to control their custom parameters. (A new post undo-close tab hook patch is pending to support the undo case.)

4. In pseudo harmony with clone-frame, add tab-bar-duplicate-tab-clone-parameters-functions hook, the user-provided functions of which would accept the originating tab, and return the list of parameters to clone.

My preference is 1, the simplest, but I can be persuaded that another on this list, or a different one entirely, is acceptable.

-Stephane