Please forgive the long post. My search of both the forum and the web suggested that such a detailed account might be of value to the development team and others.
Within an up to date Windows 7 Ultimate SP-1 64-bit system with the executables for Boxcryptor (v2.0.415.375) and OneDrive (aka SkyDrive) on (C:), with the OneDrive Store on (D:), and the Boxcryptor virtual drive auto setup to (V:), the following Boxcryptor Recycle Bin [BC-RB] behaviors are noted:
1. The default installation setup excludes the BC-RB. This is verified by two things. First, if deletion confirmations are called for, they show '... permanently delete ...'. Second, a check of the Properties of the OS's master Recycle Bin confirms that drive (V:) is not listed as a configurable drive.
2. Within the default installation setup, clicking Settings \ Advanced ... Show more settings reveals only 'Hide files/folders starting with a "."' is preselected. If you select 'Enable recycle bin' you will note that both 'Mount for all users' and 'Mount in Windows Mount Manager' are also automatically selected. After clicking OK and remounting the Boxcryptor drive, you find that the BC-RB feature is in fact working. This appears to be stable with or without 'Mount as a fixed drive' or 'Enable long path support' enabled.
3. Here is where the UI anomaly creeps in. If you start with the default installation setup then go into the extended Advanced Settings and select both 'Mount for all users' and 'Mount in Windows Mount Manager' but NOT 'Enable recycle bin', the BC-RB will still be enabled. Again this appears to be stable with or without 'Mount as a fixed drive' or 'Enable long path support' enabled.
In 2. above we see the UI auto-selects 'Mount for all users' and 'Mount in Windows Mount Manager' when 'Enable recycle bin' is selected.
It appears from 3. above that the inverse should also be true ... that is, if you select 'Mount for all users' and 'Mount in Windows Mount Manager', then the UI should auto-select 'Enable recycle bin' as well. This of course assumes that this behavior is mandated by the combined Boxcryptor / Windows 7 ecosystem ... knowledge well beyond my capabilities.
Lastly, users should be reminded to allow Boxcryptor to handle all BC-RB changes. Disabling the BC-RB when it is visible in the OS's master Recycle Bin Properties will cause permanent deletions even though the Boxcryptor UI shows the BC-RB to be enabled.