Disabling word wrap can leave a big blank gap

[TomMalbran]

Problem:

1. Open a file with long files. I tested with src/thirdparty/CodeMirror2/modes/sql/sql.js.
2. Scroll to the end of the file.
   3.1. If word wrap is enabled, disable it.
   3.2. If word wrap is disabled, enable it, scroll back to the end of the file and disable it.
3. Select the last line
4. Re-enable word wrap

Result:
3. You only see lines 260-269, since those where the lines rendered before, leaving a big gap on the top. Scrolling solves this issue.
5. You can see all the text, but the cursor is not on the screen anymore. Not a big issue, but there seems to be a big scroll difference.

Expected:
3. No blank lines.
5. Scroll stays at the bottom of the screen.

[TomMalbran]

I believe 3 can be easily fixing by doing a refresh on the current document.

[pthiess]

Reviewed @RaymondLim

[RaymondLim]

This has the same root cause as #3241. If I comment out the changes in codemirror/codemirror5@9338ba4, then the rendering issue is fixed, but not the scrolling issue after step 5 which I believe have to fix in our code.

[RaymondLim]

The main issue in step 3 is fixed in CM, but I still need to fix the issue in step 5 in my code where we turn Word Wrap on.

[TomMalbran]

I checked back into this and both issues seem fixed. The scroll doesn't move at all enabling and disabling the word wrap option. The cursor might get off the screen, but I think that should be expected if it wants to keep the scroll as before. It should be more important to keep the scroll as it was than the cursor in view.

[njx]

I had to roll back the CM SHA due to the latest upstream breaking our unit tests (see comment in #3241), so let's keep this open for now.

[njx]

FYI, the latest CM is merged again, so that aspect of this should be fixed now.

[TomMalbran]

Yes, I see the problem fixed again.

[RaymondLim]

Closing.