Gentlemen: With all due respect (and sincerely I do not wish to offend), code folding has not been a part of any language specification I have ever read. And I have read more than I care to admit. To suggest the forking of a language in order to introduce a compiler directive is to not understand the roles and differences between a "language", a "compiler" and the framework of its construction, and a text editor even one with minimal degrees of IDE functionality like Komodo.
The #region in Visual Studio (which is my primary IDE, and I am intimately familiar with VS/c#/DN) - is indeed a compiler directive. However, it is NOT part of the c# language spec, nor are compiler directives of any sort, as they are quite literally "part of a compiler language of sorts". But that's irrelevant, the point is that even as part of the compiler directive "language" (to use that term loosely) they do NOT provide the type of cold folding being discussed. That is a function of the editor, specifically, either 1: the builtin code folding capability (unlikely) or 2: the extension "bolted" onto the editor which provides the feature. VS has wonderful code folding, but it's not very flexible, configurable, and as of VS2017 not extensible unless you're willing to write a complete plugin.
If you want to see what I am talking about in action, look at Eclipse with the one code folding plugin they have worth touching. It allows you to specify tags which are folded. So - from plugin -> editor, NOT, language -> compiler -> editor.
In any case - the code folding in Komodo Edit is broken, sadly. I have found it to be inconsistent even when just dealing with a very tiny number of files that are strictly htm/js/css/php. And I have been researching the extensibility of the app to see if it was worth me writing a plugin to solve the matter. So far, I have found the extensibility to be.... lacking, and outdated. I MEAN NO OFFENSE TO ANYONE - it's still a great editor. These are just my views, after only about 2 weeks of eval time. So anyone involved with the product, or these posts, if you have been in the software world any length of time then you know not to take criticisms personally. Especially when they come from an anonymous inter-thingy user.