Visual Studio 2019: See my new Selection and TODO Highlighter extension. It has almost the same and more features and can be fully configured, finally! (Just the yellow DEBUG highlighting is missing, as I found it not very helpful.)
Visual Studio 2017: Please download the updated VSIX file from GitHub. The marketplace website won’t let me upload extensions that are compatible with VS 2010 through 2017. Say Thank You to Microsoft.
TodoHighlighter is an extension for Visual Studio 2010–2017 that places red boxes behind all the “TODO”s in the editor window, like in this description. It can also highlight other keywords, currently “DEBUG” with a yellow colour. Collapsed code regions also show the highlighting colour so that it is easily visible where such keywords exist.
Feedback: Please use the GitHub issue tracker to report bugs.