class ShellApi {

    ShellApi.AddToRecentDocs(newFilename);

    ShellApi.AddToRecentDocs(newFilename);

Someone previously thought "the truth is in the headers - in this case ShellAPI.h, which declares them all as LPCSTR i.e. they're always ANSI not Unicode.". On the contrary, shellapi.h defines two versions of the structure, SHELLEXECUTEINFOA and SHELLEXECUTEINFOW, and ShellExecuteExW expects a SHELLEXECUTEINFOW structure... so although "LPCTSTR" never appears in the definition the effect is the same.

Some of the constants were contained within conditional compilation blocks; see the commented out sections. I removed conditional compilation blocks for assumptions that like WINNT and WINVER >= 0x0400 and WIN32WINNT >= 0x0500. See ShellAPI.h for the complete source.