Sure, this text comes from MS Windows explorer's context menu when you right click mouse on the folder. I am wondering if it is correct and "Open in a new window" is not more grammatical. If it is so, why Microsoft decided to remove the article from this sentence?
1 Answer
Microsoft wanted (and still generally does) to keep things short - overly long pop-up messages can be difficult to display.
The phrase is a little terse/abrupt, but that is not unusual in this sort of context.