When I choose "Version history" or "View on Dropbox.com" in the Windows Explorer context menu of a file in my Dropbox, I get the "Usage" dialog box.
The specific URL given to BrowserSelector.exe by the Dropbox context menu command is a simple file URL on the form file:///C:/Users/MyUserName/AppData/Local/Temp/dbfidti_h6j.html#f0387784fbe3c8c15a2532530f (I changed the cryptic codes, but the pattern is the same).
I have to turn BrowserSelector completely off as default browser due to this, effectively rendering the program useless. :-(
I guess it could be solved with changing the line
if (arg.StartsWith("http://", StringComparison.OrdinalIgnoreCase) || arg.StartsWith("https://", StringComparison.OrdinalIgnoreCase) || arg.StartsWith("ftp://", StringComparison.OrdinalIgnoreCase))
to
if (arg.StartsWith("http://", StringComparison.OrdinalIgnoreCase) || arg.StartsWith("https://", StringComparison.OrdinalIgnoreCase) || arg.StartsWith("ftp://", StringComparison.OrdinalIgnoreCase) || arg.StartsWith("file://", StringComparison.OrdinalIgnoreCase))
in the file Program.cs, but I'm unsure how that affects the detections or .url files etc. in the lines that follow.