问题
When editing .pt files (which I've configured to be highlighted as XML) in MacVim, I get these funny little red arrows on the side.
What do these mean? What "feature" is this, and where can I find out more information about it?
回答1:
Those arrows are most probably added by the Syntastic plugin, you can probably remove that plugin from executing inside Janus, somehow.
Also, as mentioned in my comments. You should not use Vim distributions, and here's why:
It is considered bad practice, that's one of the big reasons. At least it is from an experienced/advanced/expert Vim user, I don't claim to be any of them, but I'm certainly no beginner. :)
But the most important reason is because it slows you down. In more than one way. It slows you down in the fact that you don't get to know Vim, because you didn't configure it, the distribution did, sure you can usually override their settings, but it's definitely not the same than if you did it yourself.
And in a bigger way perhaps, is because you need to learn everything the plugins do, AT THE SAME TIME. That's no good. This of course changes if you're comfortable with all the plugins before hand.
For example right now, you didn't add those arrows, the distribution did. And so you were confused, because you didn't know about it, but it's still there.
That's just my two cents from the perspective of an adept (if I qualify as that) Vim user.
回答2:
I don't mean to steal thunder from Eduan, but removing syntastic altogether is probably a bit exagerated as it can be a quite useful plugin.
Instead, you should read syntastic documentation, :h syntastic, and look around for the option that deals with "signs".
The advice to drop Janus, on the other hand… I completely back it up.
回答3:
It looks like you have a syntax error in the "xmlns:tal" portion of your header (something is funky-looking about that colon compared to the others in your image), although it could also just be that Syntastic is complaining about not properly understanding the .pt suffix (I do not think this is the issue). From getting Syntastic help (:h syntastic), you can find the :Errors command, which will try to give you a hint about the reason for the error. I, for example, had stupidly inserted a new element in a multi-line attribute list and googling led me here.
Of course, uninstalling Syntastic, Janus, or vim will also remove the error indicator, as others have suggested.
来源：https://stackoverflow.com/questions/14264635/what-do-these-red-arrows-in-vim-mean