Affects: indows 7 (64bit)
There should be a preview handler for the windows explorer.
As of my experience, libreOffice doesn't come with one at least until 4.2.1.
Doing some research, there's no third party or extra installable extension.
According to this thread in the libreOffice forum, there's none existing yet:
Invalid-- this is already an embedded feature of the LibreOffice installer for Windows builds--the Windows Explorer Extension
Perform a custom installation and in the Optional Components panel select the checkbox Windows Explorer Extension
It will render first page preview of ODF documents in MS Windows Explorer when folder view is set to any of: Extra Large Icons, Large Icons or Medium Icons are
The bug is not about file thumbnails. But about previews in the preview pane of Windows explorer. These previews that you can navigate through.
See also https://bz.apache.org/ooo/show_bug.cgi?id=107602#c17 where this issue has also been discussed. There is also a hint about where the problem comes from. (As a non programmer I can't tell if it's easy to solve.)
The internet is full of users complaining about this. I think solving this would be a great help for a huge amount of users!
Yes, I marked it invalid in error. More likely it ends up a WONTFIX. But with needed refactoring for bug 127433 to support Windows Dark mode, may be of dev interest to implement.
Windows shell integration is provided in core/win32/shlxthdl where ooofilt provides the current ability to search within ODF documents.
While one page 'preview' thumbnails are provided by a dedicated shlxthdl/thumbviewer that extracts a document preview if recorded into the ODF archive and makes it available to the Windows shell (needs refactoring for bug 127433).
Though LibreOffice provides a search/find capability, there is no LibreOffice provided preview of ODF in the Windows Explorer 'Preview Pane' as implemented at Windows Vista for visual browsing of documents in Windows Explorer. 
Preview Handlers get recorded to Windows registry in HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\PreviewHandlers and linked by file extension.
When installed, Microsoft Office (365, 2016) provides a Preview Handler implementation for browsing OOXML formatted documents and for some ODF formats--but these are not LibreOffice's ODF renderings.
(In reply to JS from comment #2)
> See also https://bz.apache.org/ooo/show_bug.cgi?id=107602#c17 where this
> issue has also been discussed. There is also a hint about where the problem
> comes from. (As a non programmer I can't tell if it's easy to solve.)
No, at that point in the BZ issue that discussion was only about the Microsoft Office provided 'Preview Handler' not previewing AOO documents. Seems no longer an issue with Office 365 or Office 2016 installed.
> The internet is full of users complaining about this. I think solving this
> would be a great help for a huge amount of users!
Please provide links for threads/blogs expressing rational use case, always helpful to document requirements.
This is a valid request.
Note that to enable the preview, ~full LibreOffice would need to be loaded inside the Explorer, because there's no light-weight file viewer in LO (and basically all components take part in import/layout/display of the document). I have no idea how comfortable might that delay be (or what are the implications of crashing inside the preview). I can only be sure that tdf#69043 will get worse, because more processes in more scenarios would use LO files.
The ActiveX control (that embeds LO documents to ActiveX clients) has a functionality that possibly could be re-used here.
(In reply to Mike Kaganski from comment #4)
> This is a valid request.
Okay, let's keep the request open until dev found a solution.
*** Bug 88329 has been marked as a duplicate of this bug. ***
*** Bug 136528 has been marked as a duplicate of this bug. ***
+1 for this, many people use the preview pane in the windows explorer, it would greatly improve usability / alternative to MS office.