Details for the issue

I hope to have a preset "Display format" for "datetime(key, 'unixepoch', 'localtime')".

When I select 'Unix epoch to date' as "Display format" and try to re-edit it,
the selection label becomes 'Custom' with text field of "datetime(key, 'unixepoch)".
However the text field is not editable.

Useful extra information

I'm opening this issue because:

• DB4S is crashing
• DB4S has a bug
• [ X ] DB4S needs a feature
• DB4S has another problem

I'm using DB4S on:

• Windows: ( version: ___ )
• [ X ] Linux: ( Fedora28 )
• Mac OS: ( version: ___ )
• Other: ___

I'm using DB4S version:

• [ X ] 3.10.1
• 3.10.0
• 3.9.1
• Other: ___

I have also:

• Tried out the latest nightly version: https://github.com/sqlitebrowser/sqlitebrowser#nightly-builds
• Searched for an existing similar issue: https://github.com/sqlitebrowser/sqlitebrowser/issues?utf8=%E2%9C%93&q=is%3Aissue%20