Below piece of code does not provide guarantee about detecting WinXp and Win2K

From "ScintillaEditView.h"

void convertSelectedTextToLowerCase() {
         // if system is w2k or xp
         if ((NppParameters::getInstance())->isTransparentAvailable())
                  convertSelectedTextTo(LOWERCASE);
         else
                  execute(SCI_LOWERCASE);
    };

whereas transparentFuncAddr points to "SetLayeredWindowAttributes".

    // Transparent function for w2k and xp //
    //-------------------------------------//
    HMODULE hUser32 = ::GetModuleHandle(TEXT("User32"));
    if (hUser32)
        _transparentFuncAddr = (WNDPROC)::GetProcAddress(hUser32, "SetLayeredWindowAttributes");

I was debugging issue #2417 on Win10. As code is running on win10, I expected to statement execute(SCI_LOWERCASE); (from code snippet 1) to be executed, but it goes to convertSelectedTextTo(LOWERCASE);

In convertSelectedTextTo(LOWERCASE), API CharLowerW does not convert uppercase dotted (İ) to lowercase.
As per MSDN https://msdn.microsoft.com/en-us/library/windows/desktop/ms647467(v=vs.85).aspx unfortunately, there is no indication of success or failure. However, failure is rare. :(

So concerns:
1: Why npp does not hand over case conversion task Scintilla?
2: If Scintilla conversion does not work properly on winXp and Win2K, condition to check winXp and Win2K should be modified, So issue #2417 (or similar) will not occur atleast on Win10 as execute(SCI_LOWERCASE); working perfectly.

Notepad++ v7 (32-bit)
Build time : Oct 13 2016 - 23:29:49
Path : C:\Program Files (x86)\Notepad++\notepad++.exe
Admin mode : OFF
Local Conf mode : ON
OS : Windows 10
Plugins : DSpellCheck.dll mimeTools.dll NppConverter.dll NppExport.dll PluginManager.dll