Welcome Dialog dark theme status initially wrong

Summary:

Welcome dialog on startup uses system theme but toggle are not changed accordingly.

Steps to reproduce:

• Open inkscape
• Notice theme toggle in Quick Setup tab
• Toggle theme
• Toggle again

What happened?

In my case my system (OS) theme was dark. But initially inkscape toggle was set on light theme. When pressing it first time it toggles to black (black to black).

What should have happened?

Initial toggle should be set to system theme or inkscape should not read system theme on first startup

Sample attachments:

Version Info:

- Inkscape Version: Inkscape 1.1-alpha (ae80b40637, 2021-03-23)
- Operating System: Pop!_OS
- Operating System version: 20.10