Scroll up under inverted=NO when keyboard shows

[zhubofei]

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PR Summary

Scroll up to current place when keyboard shows

Related Issues

#466

[zhubofei]

Flaws:

• There is still a magic number "64" in this solution. It is the height of the navbar.

[zhubofei]

Fixes #466

[zhubofei]

#542 is much better than my solution. I'll just close this PR.

[dzenbot]

That's good to know. Thanks for the headups @zhubofei !