future

Describe the bug
If the code editor's width has been changed, opening a new file via the file browser resets the width to the default

To Reproduce

1. Drag the edge of the code editor pane to resize it
2. Switch to a different file via the file browser

Result: The code pane width will be reset

Expected behaviour
The code pane width should remain the same

![code_pane_widt

The mapcat function seems to choke if you pass in a mapping function that returns a stream instead of a sequence:

user> (s/stream->seq (s/mapcat (fn [x] (s/->source [x])) (s/->source [1 2 3])))
()
Aug 18, 2019 2:23:39 PM clojure.tools.logging$eval5577$fn__5581 invoke
SEVERE: error in message propagation
java.lang.IllegalArgumentException: Don't know how to create ISeq from: manifold.