Your plugin should be in the ..\..\IDE\Plugins\Runtime folder.
You can change this in the properties of the TemplateSDK under Configuration Properties -> Linker -> General -> Output File.
I have the same problem with the grey text in Eddittime.cpp. The grey text will not compile because the compiler directive RUN_ONLY isn't defined anywhere.
Can anyone help us n00bs?
Edit:Never mind, I figured it out.
You're actually making 2 plugins: 1 for the edit mode of Construct, and 1 for when your game is running.
The code is laid out so that when you are editing the Layout part, the runtime code is greyed out, and vice versa. To switch between the 2, you can select "Debug" and "Debug Runtime" at the top of the screen in Visual Studio. It takes a few seconds for the editor to catch up, so don't panic if the text doesn't immediately turn normal.