title: Surprise frontend requirement after splitting backend into 2 projects
body: <p>I had 2 projects in my solution. One WPF frontend and one C# library backend. This worked fine for month, but now I decided that a part of the backend has become complicated enough that I would split it off into it's own, third project.</p>
  <p>So now I have 3 projects: 1 with most of the backend code that depends on nothing, 1 other backend code that depends on the first for interfaces, and 1 frontend that depends on the other 2 projects.</p>
  <p>There were some namespace changes that I had to fix throughout the code, but else it's a straight forward change. Or so I would think. Because now my frontend suddenly has a requirement for <code>Microsoft.Xaml.Behaviors</code> that was not there before I split the projects (the error tells me it's required for the Xaml triggers that worked fine before).</p>
  <p>I tried around adding references to the backend projects thinking that they may be required for some inheritance reason, but that didn't change anything. Only when I imported the Microsoft.Xaml.Behavior.WPF Nuget package to the frontend was the reference resolved.</p>
  <p>The weird thing is that I have 0 frontend changes. I can check out the previous commit and the requirement is gone. All that is changes for the frontend are some namespaces and the added reference to the new project.</p>
  <p>Where does the requirement suddenly come from?</p>