add support for blocking screenshots being taken

Checklist

• I have used the search function to see if someone else has already submitted the same feature request.
• I will describe the problem with as much detail as possible.
• This issue only contains a request for one single feature, not multiple (related) features.

App version

5.807

Problem you are trying to solve

Reduce the amount of personal information being disclosed should an android device be compromised with malware

Suggested solution

I am aware that this is not a perfect privacy solution and there are ways around it but it would be useful to have K-9 block the ability to take screenshots.

While the risks / concerns of someone remotely taking a screenshot of K-9 on most peoples devices phone are low there are still users who are high risk, it is a possibility that some malware is setup to take screenshots of open apps. Given the nature of email this could include sensitive information

Additionally with screenshots blocked, switching apps would result in you seeing k-9 is your list of open apps but not seeing the screen it's contents

My suggestion would be to add a toggle option to settings -> general settings -> privacy that would allow people to toggle on or off the blocking of screenshots.

Some apps that do that have this option if examples/comparison is needed

• Signal (allows toggling screenshot capture on or off)
• Protonmail (always blocked)
• Aegis (allows toggling screenshot capture on or off)

Screenshots / Drawings / Technical details

discussion of possible ways to do this here

Start by reviewing the Android screen-capture prevention approaches linked in the issue and the Settings > General settings > Privacy path described there. Identify where this privacy toggle belongs and verify that enabling it blocks screenshots and app-switcher previews while disabling it restores normal capture behavior.