DropBox
Overlay Icons
HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Explorer\ShellIconOverlayIdentifiers
http://superuser.com/questions/809529/which-dropbox-icon-is-for-which-icon-overlay-identifier-name
Name
Color
Meaning
DropboxExt1
Green
Synced!
DropboxExt2
Blue
Sync in progress
DropboxExt5
Red
Sync not happening
DropboxExt7
Gray
A folder isn't syncing