Cinnamon settings does not affect Gnome application's clock format

[forever-and-a-day]

 * csd version  4.6.4+ulyana
 * Distribution - Mint 20
 * Graphics hardware *and* driver used - NVIDIA RTX 2070 Super, nvidia-driver-450 version 450.80.02-0ubuntu0.20.04.2
 * 64 bit

Issue
Date and time settings for "use 24 hour clock" do not carry over to gnome applications. See org/gnome/desktop/interface/clock-format in Dconf Editor. While experienced users may find this key and change it themselves, cinnamon settings should do this by itself.

Steps to reproduce
system settings>date and time>turn off "use 24 hour clock"
attempt to create or modify an event in gnome-calendar, or use gnome-clocks, etc. Still in 24 hour time. Changing org/gnome/desktop/interface/clock-format in Dconf Editor to 12 hour time makes relevant applications use 12 hour.

Expected behaviour
cinnamon-settings-daemon should change the necessary keys to make gnome applications use 12 hour or 24 hour time.

Other information
N/A

[ItzSwirlz]

hmm.. I think this could be an option. Have a schema in cinnamon settings asking if the user wants to globally change the time to other applications, then somehow we can probably send the dconf change to programs.. but they would only really be if they were around. This would lead to an if-program-is-found type problem but again, an option would be good.

[ItzSwirlz]

Schemas that should be changed ideally:

org.gtk.settings.file-chooser.clock-format
org.gnome.desktop.interface - all clock stuff can be adjusted towards cinnamon

[Fantu]

When replace of datetime plugin will be done for solve #315 rebase also of cinnamon-control-center datetime panel can (or must) should done and this will be solved.
from a fast grep actually clock-format is not found in cinnamon-control-center but in gnome-control-center datetime panel is present

[collinss]

@Fantu fyi, the cinnamon-control-center datetime panel is no longer used. It was ported to cinnamon as a native python module.