You can use Acrolinx browser extensions to check content in many web applications. But sometimes Acrolinx cannot read the content and you'll see the message "Where's the text?"
Why can't Acrolinx read the page from my web application?
There are different reasons why something can go wrong.
What kind of element does my web application use as an edit component?
1. Right-click the edit box -> inspect (element)
2. Navigate up in the html tree and watch out for significant elements.
4. Go up in DOM:
5. In this case you find
<div contentEditable="true"> ... </div>
That means that in principle the sidebar could extract the text.
...but if you go further up you see that the content editable div is in an iframe from a different URL so it will not work:
Let's look at another example:
Here is a content editable div. It is served from the same URL. In this case it works.
Another working example - text area on the same page:
Here is another example where it works (wordpress live demo). There is a content editable div in an iframe. The iframe of the tiny mce is served from the same origin so that it works.