fix: make sure that menu bar gets focus even when you click an item to focus it first

[brenca]

Description of Change

Pretty much what the title says, right now, if you click on the menu bar and hit Esc, you can't use the arrow keys to navigate because the menu bar itself never got focus. This fixes that.

Checklist

• PR description included and stakeholders cc'd
• npm test passes
• PR title follows semantic commit guidelines
• PR release notes describe the change in a way relevant to app developers, and are capitalized, punctuated, and past tense.

Release Notes

Notes: Fixed a bug where you couldn't navigate the menu bar with the keyboard if you used the mouse to focus it.

[erickzhao]

Can confirm that this works for me on both Windows 10 Pro and Ubuntu 19.04!

[release-clerk]

Release Notes Persisted

Fixed a bug where you couldn't navigate the menu bar with the keyboard if you used the mouse to focus it.

[trop]

I have automatically backported this PR to "7-0-x", please check out #19762

[trop]

I have automatically backported this PR to "5-0-x", please check out #19763

[trop]

I have automatically backported this PR to "6-0-x", please check out #19764

[nornagon]

This seems to have reintroduced an issue that #19708 fixed, namely that clicking the menu bar causes the main window to lose focus.

[erickzhao]

Looking back, that does make sense as giving focus to the menu bar might un-focus the input fields. I wasn't careful enough to check the Fiddle example for issue #18745 w/ this PR.

I don't have access to a dev setup on Windows or Linux at the moment, but maybe @brenca would have an idea?