Visually separate pinned and unpinned streams while searching

[preetmishra]

The first commit is a refactor that extracts streams_view_divider() from streams_view().

The streams_view_divider() is used in the second commit, in update_streams, for inserting a divider between search results.

Fixes #577.

[kaustubh-nair]

@preetmishra This looks like a useful visual improvement 👍
One bug I noticed is two lines are displayed if I search for something then clear the text with backspace.
(Oops closed the pr by mistake)

[preetmishra]

@kaustubh-nair Thanks for the bug report. 👍

I couldn't notice it initially it as I only have a few streams pinned and the stream list would update past the pinned streams whenever I cleared the search with backspace (#700 will fix this). However, with a bunch of streams pinned, it was pretty straightforward to reproduce.

I have pushed an update that will resolve the bug.

[neiljp]

@preetmishra This looks good 👍 I'm surprised how much of a difference this makes to the search result display, but it demonstrates how we order the results, which perhaps explains why :)

As per my inline comment, I think the refactor doesn't belong in helper.py. That's both since we're basically generating a UI element, and if we treat it as literally a subclass then it fits with the others in UI files; it also has the workaround which refers to the StreamButton, so that points towards keeping it together with UI code too. We don't note what to have in helper.py, but I'd prefer to limit it as much as possible, where the code could belong with the other M/V/C components.

[preetmishra]

@neiljp Thanks for the review and the pointers.

I have extracted the divider as a subclass now and moved it into in views.py. The subclass does improve readability and make it cleaner and the code does fit better in views.py.

[neiljp]

@preetmishra Just a few minor points to consider 👍

[preetmishra]

@neiljp Thanks for the review. I have incorporated all the suggestions in the latest update.

[neiljp]

@preetmishra Thanks for working on this! I'm merging this now 🎉