If I create a CodeMirror instance and set it with a height, it will initially show with the correct height.

If the component with the CodeMirror is removed from and returned to the DOM via conditional rendering, the height is lost.

I've created a sandbox here to demonstrate.

Steps to reproduce:

1. Load sandbox
2. Note how the height is 500px (this is CodeMirror)
3. Edit text (press the 'o' key and type some stuff)
4. Click Show Diffs button (this opens CodeMirrorMerge)
5. Abandon, Save, or cancel (back to CodeMirror)
6. Note how the height is no longer set to 500px.

I've read that there is a refresh and/or an autorefresh cm command that might address this issue, but you probably know better than I do.