This is an experimental feature that can be extremely helpful, especially for editing Regular Expression patterns inside String literals due to the double escaping requirement. For example, in a regular expression, a literal backslash character has to be written as a double backslash and each of them has to be escaped with another backslash when written inside a String literal.
The Quick Edit function that appears as an Intention Action for any injected language fragment displays a popup that allows you to edit the string's value without the double escaping requirement. The dialog also shows the particular prefix/suffix of the fragment in a non-editable area.
The popup can be dismissed by pressing Escape or clicking somewhere outside the popup. Any changes made in the popup are committed by pressing Ctrl-Enter.
Please note that the formatting of the non-editable prefix/suffix may differ from the actual value due to some problems. However, even though the formatting/alignment of the editable text may differ from the expected text, making changes to the text still works as expected.
warning
Accepting Inspection Quick-Fixes inside the QuickEdit popup may cause strange things to happen when the Quick-Fix attempts to open an Editor for the element being edited. The Create Method Quick-Fix of the JavaScript language is an example for that.