On Friday I tried to update one of the legacy DataSets of the application I’m working on. When I double-clicked the data set schema, VS just opened the XML view to edit the schema. Quite useless. So I right-clicked the item and selected “View Designer” which then brought up a new window that contained all the inner text of the XML document as one large blob. More than just useless…
Today I started looking for a solution or possible cause for the problem. It would seem that the data set designer was not loaded on VS startup. The solution then was quite simple: Open a command line and start

devenv /resetskippkgs

This tells VS to reset its list of skipped packages and load everything. Now I can use the designer again.