[Unity 5.3.6f1] Opening .cs and .json Files in StreamingAssets Folder Opens New VS2015 Window

Hi there,

I wanted to open my item database file, which is a .json file, from within the StreamingAssets folder; however, it opened a new Visual Studio window, instead of just opening a new tab in the current window I already have opened. I've put a .cs file in the StreamingAssets folder as well to test it, and the same thing happens.

I'm guessing this has to do with the fact that the files in this folder aren't built by Unity, since the icon for the .cs file changed to the one used by Windows in the Unity editor when I put it in. Is there a way to curb this behavior? It works when I drag the file into my existing window, but it would be more convenient if I could just click.