codemirror/CodeMirror — pull request #2884 by jparmenter (2014-10-19 22:59:36+00:00)
Title: [gfm] Added strikethrough implementation

Resolves #1887. Added strikethrough implementation. I followed the code from strong since that seemed similar to strikethrough. Also @bfrohs was a major help!

There are some problems with my implementation that I would love to hear some feedback on to improve the pull request.

* Tabs are not being picked up by the editor. Couldn't seem to write a test for it.
![strike tab](http://i.gyazo.com/65ceb88b3d67ec740e2ed9f631c0b239.png)
* The following test fails though I can't find the problem with my code.

```javascript
MT("strikethroughWrapped",
"[strikethrough ~~foo]",
"[strikethrough bar~~]");
```
* Problems when editing inside the strikethrough.

* Editing after the fist line of strikethrough removes it.
![strike tab](http://i.gyazo.com/87fff59b5fc8bdc8291d1acc5d272a33.gif)

* Editing on first line resets strikethrough to how I expect.
![strike tab](http://i.gyazo.com/66b2ac7a1120337990a2c90d20feea8e.gif)

* Joining lines doesn't add strikethrough unless first line.
![strike tab](http://i.gyazo.com/b533cad9afff5cd004a809c256ed7d56.gif)