The progressive, according to the horribly named 外国人实用汉语语法 (A Practical Chinese Grammar for Foreigners), looks like
正在 + predicate (verb) + 呢with any part of the aspect marker being optional. This pattern describes an ongoing action.
Which is different from the continuous, which indicates an ongoing state of affairs, having the appearance of
predicate (verb) + 着which, in English, can look adjectival.
1. 我正在开窗户。 I'm (in the middle of) opening the window. [progressive]
2. 窗户开着。 The window is (now) open (after already having been opened). [continuous]