Describe the problem

When accessing office documents (Excel, Word, etc.) through a public share link in Collabora Online (EDIT: while also being logged in with an account with access to that file), the Share button appears fully enabled and clickable in the toolbar. However, clicking it produces no visible result. The only indication of failure is a console message: [FilesAppIntegration] Sharing is not supported.

This created confusion as I expected the button to work, or at minimum, to provide some feedback explaining why it doesn't.

Steps to reproduce

1. Create a public share link for an office document (e.g., .xlsx file)
2. Enable editing permissions on the share
3. Open the share link (even with an active Nextcloud session)
4. Once the document loads in Collabora Online, observe the toolbar
5. Click the "Share" button in the top-right corner
6. Observe that nothing happens

Expected behavior

In my opinion, the Share button could provide some feedback about why it's not working. Some possible approaches might be:

1. Disable/grey out the button with a tooltip (e.g., simply "Public Share")
2. Hide the button entirely when FilesAppIntegration is not supported
3. Show an error message when clicked explaining the limitation
4. Add some visual indicator that the button is in a restricted mode

However, I'm not a UX expert - the development team would know best what approach fits the overall design philosophy.

Actual behavior

• Button appears fully enabled and clickable
• Clicking produces no visual response
• No error message or feedback is shown
• Only evidence of failure is a console message ([FilesAppIntegration] Sharing is not supported) which I wouldn't normally see
• I kept clicking expecting it to work, thinking the feature might be broken
• This occurs even when logged into Nextcloud - it's the access method (public share link) that causes the issue, not the authentication state

Impact

This affected my experience because:

• I was trying to access file management features and got no feedback
• I didn't realize that accessing via a public share link would limit functionality
• I had to dig into the browser console to understand what was happening
• It wasn't clear that I needed to navigate to the file through Nextcloud Files instead

System information

• Nextcloud version: Nextcloud Hub 10 (31.0.10)
• Nextcloud Office (richdocuments) version: 8.7.6
• Collabora Online version: Collabora Online Development Edition 25.04.6.1 (c042625181)
• Browser: All browsers affected

Additional context

The code in Office.vue shows that revisionHistory: !this.isPublic is set, intentionally disabling file management features for public shares. This makes sense from a security/permissions standpoint, but the UI doesn't currently reflect this limitation.

Console output when clicking Share button:

[viewer] Received post message UI_Share 
Object { }
false Office.vue:373:1

[FilesAppIntegration] Sharing is not supported