I'm entirely sure that this should be reported as a bug vs. a feature, however:

As a user connected to some deployment using Compass:

• I can click the Aggregations tab
• I have created at least one stage in my pipeline
• If my stage results preview contains nested documents and I have expanded one or more of these nested documents ...
• Making any keystrokes (including whitespace in an effort to increase the height of my expression input and thus the results preview area for demo purposes) within the expressions input will re-trigger the pipeline and my previously expanded documents will collapse

It might be useful to be able to expand nested documents and have their expanded state persist.

Screenshot:

cc asya