Use a different scheme for Writer and Calc

I would like to use a dark background in Calc so I modified the scheme to do so (Tools → Options → LibreOffice → Application Colors → Document background).
But I don’t want this scheme change in Writer.
Is there a way to have a different scheme for Writer and Calc?
Or at least a keyboard shortcut to switch scheme, or a menu button?

By setting UserInstallation environment variable, you may change the profile location of started LibreOffice instance. Each profile may define its own scheme, and so each such instance may have different appearance. This method allows using single installation, without need of multiple installs.

So, you may create shortcuts like that:

path/to/soffice.exe "-env:UserInstallation=file:///path/to/appdata/LOProfile0/" --writer

path/to/soffice.exe "-env:UserInstallation=file:///path/to/appdata/LOProfile1/" --calc

and use them to launch different instances of LibreOffice with Writer and Calc (respectively) already open.

However, there are a number of things to be aware of:

  1. The instances will be separate, so memory requirements would be higher than in conventional method, where single LibreOffice instance is used for both modules.
  2. You still may open other modules from each instance, since there’s no method to disable a module in a user profile.
  3. Each extension installed for user will not be available in another profile, and would require to be installed there, too (if required).
  4. These profiles need to be launched manually. Default system integration would still use single profile for launching all typed of files associated with LibreOffice. You might adjust this manually, though (on Windows, this requires changes to system registry).

Thanks for your clear and detailed answer.

You can’t have different schemes for Writer and Calc at the same time because basically Writer and Calc are just frontends to common core modules. The color scheme is in a configuration file that is read on LibreOffice startup. Namely, it is <user profile directory>/registrymodifications.xcu.

Thus, if you want to quickly swap the color schemes:

a) modify the settings as you need them for Writer and make a copy of registrymodifications.xcu, say, registrymodifications.xcu.writer;

b) modify the settings as you need them for Calc and make a copy of registrymodifications.xcu, say, registrymodifications.xcu.calc.

Now, before you start Writer, copy registrymodifications.xcu.writer to registrymodifications.xcu. Respectively, before you start Calc, copy registrymodifications.xcu.calc to registrymodifications.xcu. A convenient way is, obviously, to write a shell script/batch file.