First let me admit I don't really understand this stuff ... For anyone who's interested, this (I think) is a summary of my observations. You may prefer to jump to the TL;DNR
The non-appearance of one or more of the 3 calibre programs (Main, Editor, Viewer) in a Win10 Explorer right-click OpenWith sub-menu is something to do with the fact that calibre adds an item called
AllowSilentDefaultTakeOver during the
register process mentioned by Kovid in post #7. This is for all valid calibre filetypes.
If I manually edit the registry to remove the
AllowSilentDefaultTakeOver item from either:
Code:
HKEY_CLASSES_ROOT\calibre64bit.AssocFile.EPUB
HKEY_CLASSES_ROOT\calibreEditor64bit.AssocFile.EPUB
HKEY_CLASSES_ROOT\calibreViewer64bit.AssocFile.EPUB
or:
Code:
HKEY_CURRENT_USER\Software\Classes\calibre64bit.AssocFile.EPUB
HKEY_CURRENT_USER\Software\Classes\calibreEditor64bit.AssocFile.EPUB
HKEY_CURRENT_USER\Software\Classes\calibreViewer64bit.AssocFile.EPUB
then calibre Main, Editor or Viewer will be become permanently visible in the .epub right-click OpenWith sub-menu after its first selection from browse more apps. I'm not really sure about this but it's possible that if one of these is the Default App then it's automatically on the sub-menu.
Apps which are not calibre-related seem to automatically be visible in the OpenWith sub-menu for .epub after their first selection, e.g. MS Edge, SigilPortable (probably also fully-installed Sigil).
As far as I can tell the only appearance in my Win registry of
AllowSilentDefaultTakeOver by anything other than calibre is by the old MS WordPad prog (where
xxx is one of rtf, docx, odt) in:
Code:
HKEY_CLASSES_ROOT\xxxfile
HKEY_LOCAL_MACHINE\SOFTWARE\Classes\xxxfile
My conclusions are corroborated by the following observations about calibre and .kepub files. I had no problems getting any/all of calibre Main, Viewer, Editor added to the .kepub right-click OpenWith sub-menu. I know kepub is not a valid format for the Editor, but Windows is happy to open the Editor and calibre will gracefully give an error message about the invalid file format.
Currently calibre does not add the following to the registry during the register process in post #7:
Code:
HKEY_CLASSES_ROOT\calibre64bit.AssocFile.KEPUB
HKEY_CLASSES_ROOT\calibreEditor64bit.AssocFile.KEPUB
HKEY_CLASSES_ROOT\calibreViewer64bit.AssocFile.KEPUB
HKEY_CURRENT_USER\Software\Classes\calibre64bit.AssocFile.KEPUB
HKEY_CURRENT_USER\Software\Classes\calibreEditor64bit.AssocFile.KEPUB
HKEY_CURRENT_USER\Software\Classes\calibreViewer64bit.AssocFile.KEPUB
hence no
AllowSilentDefaultTakeOver registry additions related to .kepub.
I was able to revert any manual registry changes I made by running Kovid's suggestion in post #7.
TL;DNR ---------------------------------------------------------------
My problems getting calibre Editor and Viewer to appear on File Explorer's (and in my case, xPlorer2's) right-click OpenWith sub-menu for .epub files disappear if I manually remove
AllowSilentDefaultTakeOver from calibre-created registry entries for .epub.
I'm not sure why BetterRed doesn't see the same problems I see, unless perhaps his copy of calibre is calibrePortable rather than a fully installed one???
I'm going to assume calibre does things the way it does for good reason, so I'll need to make a couple of minor manual registry edits. The only questions I have are whether they will survive the next upgrade for:
- calibre
- Windows
I'm guessing
yes for Windows, but not too sure about calibre.