I’ve just released the new Task Canvas extension for Visual Studio 2015 that lets you edit multiple methods in a special window and quickly switch between document groups:

The general idea is to provide a task-focused interface working with code in Visual Studio, reducing information overload and making multitasking easy. Specific code block level editing allows you to concentrate exactly on your current task. Placing multiple editors in a single window reduces tab switching. Saving open document tabs and code blocks allows instant switching between tasks, most useful when you have repeatable periodic tasks or work on several tasks in parallel.
Please, give it a try and let me know what you think!
See more detailed description on the Task Canvas homepage. Download the installer.