Users can leave Block Theme Previews without noticing

[okmttdhr]

Description

In the following cases, users can "leave" the Block Theme Previews, which means users cannot activate a previewing theme. See the reproduction instructions below.
This should be addressed to allow the URL query ?wp_theme_previews= to be retained.

Step-by-step reproduction instructions

1. Go to /wp-admin/themes.php and click the Live Preview button for a Block theme
2. Click the preview to open the edit canvas -> Click the command center and navigate to another part of the Site Editor, e.g., a header or footer template part.
3. Observe the URL query ?wp_theme_previews= has gone and the subsequent page transitions occur without the URL query, which means users have no way to activate a theme.

Screen.Recording.2023-08-25.at.14.37.44.mov

Replacing step 2 above with one of the following will also reproduce the bug;

• On the Patterns menu, click Create pattern
• On the Patterns menu, click Create template part

• On the Patterns menu, click Copy to My patterns
  

• On the Templates menu, click + sign and add a new template
  

• On the Pages menu, click + sign and add a new page
  

Screenshots, screen recording, code snippet

No response

Environment info

• Gutenberg 16.5.0
• WordPress 6.3

Please confirm that you have searched existing issues in the repo.

Yes

Please confirm that you have tested with all plugins deactivated except Gutenberg.

Yes

[annezazu]

@scruffian wanted to flag this for you as there are some improvements to look into, perhaps for 6.4.