It is possible in apt to hold back updates if they would install/remove other packages. But to keep the user informed about these updates I use the blocked info for those. Gpk-update-viewer should not select them by default in the review pane or even not allow to select them at all.
Sure, valid. Should they just be unticked or unticked and greyed out (unclickable)? If it's the latter there'll need to be some sort of message to the user.
Grey out. An alternative would be to show the required changes (this could include the removal of other packages), but can we do this with get-depends?
Created attachment 18773 [details]
fixed in git
It now looks like this in git.
I don't think it's a good idea to show the user any sort of detail -- the concept of a blocked update just needs explaining in the help file, and then the user can drop to apt-get or similar if the blocked update needs to remove other stuff to continue. For the typical end users (http://www.packagekit.org/pk-profiles.html) I don't think it's important to show details.