Wrong colorization in editor for ``` code blocks

[ljw1004]

Here's a picture to illustrate the problems:

• Sometimes the language-name is green, sometimes black (should always be black)
• Sometimes some non-indented code lines are green, sometimes black (should always be green)
• Sometimes the closing-triple-blacktick is mixed colors (should always be black)
• Sometimes the paragraph following the closing-triple-backtick has the wrong colors (I'm not sure what's going on here)