Problem

Even though a folder, drive etc. is encrypted the DESlock+ icon is not being displayed correctly within Windows Explorer.

Cause

When third party software such as DESlock+ needs to display additional images over the top of the normal Windows icon such as folder and file icons, a Windows programming interface is used called  IShellIconOverlay.  Any third party software has to use this interface to provide overlay icons.

Unfortunately the Windows operating system only provides support for fifteen different overlay icons in total.  This is detailed by Microsoft in the following article:

https://msdn.microsoft.com/en-us/library/windows/desktop/bb761273%28v=vs.85%29.aspx - 'IShellIconOverlay interface'

"The number of different icon overlay handlers that the system can support is limited by the amount of space available for icon overlays in the system image list. There are currently fifteen slots allotted for icon overlays, some of which are reserved by the system. For this reason, icon overlays should be specified only if there are no satisfactory alternatives."

The operating system itself will use up a fixed amount of the slots.  For example Windows 7 can take up 5 of these slots for its own use.

If you have other software installed which also uses overlay icons then this limit may have been reached.  Reaching the limit will lead to either DESlock+ or other overlay icons from no longer being displayed. 

The list of software installed overlay icons can be seen by running regedit and viewing the registry key, these are in addition to the slots used by the operating system itself: HKEY_LOCAL_MACHINE\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\ShellIconOverlayIdentifiers

An example is shown below of a system with OneDrive, DropBox and DESlock+ installed. 

The list of entries within the ShellIconOverlayIdentifiers registry key is processed in alphabetical order.  Once fifteen entries from the operating system itself or the registry keys have been processed, any further overlay entries will be ignored.

Some providers have prefaced their entries in the registry with a space character, this maintains their position at the top of the list alphabetically improving their chance of being one of the fifteen loaded.

Due to the limited space it is important that software uses as few overlay icons as possible.  The DESlock+ client uses only 3 of the available slots.

Solution

Providing you have encrypted the drive/folder etc. using the DESlock+ interface correctly then the content will be encrypted even though visually the interface is misleading. 

If you logout of DESlock+ then try to access the container it should block your access confirming the encryption is working correctly.  Please here for details of using the Logout option: How do I login to or logout of DESlock+?

In order to allow the DESlock+ overlay icons to be displayed space will need to be made in the list.  By uninstalling other third party software it should remove their entries freeing up space.  Once you have made enough space in the list you will need to ensure you logout and back in to your Windows profile or restart Windows in order for the DESlock+ overlay icons to be displayed.

Keywords: dropbox, google, onedrive, sky, overlay