Selection jiggles while resizing window horizontally

[redmunds]

Recipe:

1. On any page, find/create a line of text with > 60 chars
2. Select roughly the middle 1/3 of the line of text
3. Change the width of brackets app

Results:
The painting of the selection highlighting briefly changes with the width of the window (seems to be a percentage of viewport width). It quickly snaps back to the correct size, but there is enough delay to make it very noticeable.

Expected:
Selection highlighting does not change with editor window width

This seems to be caused by recent CodeMirror changes.

[peterflynn]

Definitely a regression from the last CodeMirror merge. Probably same cause as #1267. Marijn has already pushed up a fix for that, so I'll test whether it covers this case too.

[peterflynn]

Confirmed this is now fixed in CodeMirror upstream -- next sprint's CM merge will give us a fix

[pthiess]

Reviewed thats opened for Sprint 12. Waiting to get the fix in CM.

[peterflynn]

The CodeMirror merge has been deferred to Sprint 13 due to some recent instability in the CM scrolling code. Pushing this bug out till then.

[peterflynn]

This seems much harder to reproduce in brackets-shell, but it's definitely still there (noticeable especially on my older Mac).

[njx]

Turns out the fix in CodeMirror (which we've merged) doesn't fully fix this case, though it does reduce how often it happens. I've filed codemirror/codemirror5#745 on this, so we can continue to track it. Removing sprint 13.

[gruehle]

This is fixed in CodeMirror v3 branch. See codemirror/codemirror5@314e7ea

[redmunds]

Confirmed that this is fixed in cmv3 branch. Closing.