PasswordBox: Password reveal button is not shown any longer when re-entering the control

Describe the bug By default the PasswordBox shows a password reveal button when the PasswordBox has focus and some content. However, when stepping out of the PasswordBox and then back into it, the password reveal button is no longer shown. Instead, the user will first have to clear the PasswordBox and then start typing again for the reveal button to show up.

Steps to reproduce the bug

1. Open the XAML Controls Gallery app and go to the PasswordBox page.
2. Start typing into a PasswordBox so that the reveal button is shown
3. Set focus on another UI element, then re-enter the PasswordBox

Observe that the reveal button is no longer shown even though the PasswordBox has both focus and content.

Expected behavior The password reveal button should be shown when re-entering a PasswordBox with content.

Screenshots (A focused PasswordBox with focus and content, yet no password reveal button.)

Version Info

Windows app type:

UWP	Win32

Windows 10 version	Saw the problem?
Insider Build (xxxxx)
May 2020 Update (19041)	Yes
November 2019 Update (18363)
May 2019 Update (18362)
October 2018 Update (17763)
April 2018 Update (17134)
Fall Creators Update (16299)
Creators Update (15063)

Device form factor	Saw the problem?
Desktop	Yes
Xbox
Surface Hub
IoT

[YuliKl]

Thank you, our docs team loves user contributions!

[Felix-Dev]

@YuliKl I would just open a PR with the updated documentation instead (and link it here). Will get the change faster into this docs based on previous experiences 😃