The file in sendto directory is Bluetooth Devices.CSRBTSendToClass.
Is Preferences / Miscellaneous / Windows Integration / Hide Windows items on file context menus (shift overrides) turned on?
It's also worth checking that the menu appears in other programs -- e.g. run Notepad and then use File/Open and see if it appears on the right-click menu there -- in case it has excluded itself from everything but Explorer.
1, confirmed turned off
2, confirmed it shows in every x64 program correctly but only dopus.
I think it maybe the reason is that currently dopus can't shows the 64bit sendto menu items?
Where does that idea come from?
If you look in the /sendto folder/alias, you'll see several standard Windows SendTo destinations which use shell extensions, and which work in Opus. They will be 64-bit shell extensions, because 64-bit Opus (like 64-bit Explorer) doesn't use 32-bit ones. So they definitely work.
e.g. "Desktop (create shortcut).DeskLink" or "Documents.mydocs" both work in Opus.
If you look in RegEdit, the extensions for that type of SendTo item should be found under HKEY_CLASSES_ROOT, and below each one should be a PersistentHandler key, with the main key and the one below it each having values that point to IDs of the involved shell extensions and other COM objects:
I doubt we'll be able to install the CSR Bluetooth drivers without the hardware that goes with them, but what do you see under HKEY_CLASSES_ROOT.CSRBTSendToClass?
No such item, but I found .CSRBTSendToClass under HKEY_CURRENT_USER\Software\Microsoft\Windows\CurrentVersion\Explorer\FileExts\ and it actulaay works in the other 64bit apps, why?
I created a HKEY_CLASSES_ROOT.CSRBTSendToClass by myself and insert the CLSID with the ID I found before, it works now.
Thanks for the details!
I'll check the code as we may not be looking for Send To items under the alternative FileExts key. That would explain what was going on.