I’ve had the pleasure of working with XAML lately. When running a XAML application from Visual Studio in debug mode, this nifty little toolbar is placed on top of windows:

While I have no doubt this can be useful, I often find it annoying too, so here’s how to remove it:

Open Tools and Options from the menu, and search for “Visual” in the top left corner. Remove the tick from the highlighted checkbox, and hey-presto, no more unwanted elements in your UI!