minor fixup: updated util function signature.

src/ImGui.NET/ImGui.Manual.cs

@@ -403,7 +403,7 @@ namespace ImGuiNET
             {
 
                 int textToCopyLen = length.HasValue ? length.Value : text.Length;
-                textByteCount = Util.CalcUtf8(text, start, textToCopyLen);
+                textByteCount = Util.CalcSizeInUtf8(text, start, textToCopyLen);
                 if (textByteCount > Util.StackAllocationSizeLimit)
                 {
                     nativeTextStart = Util.Allocate(textByteCount + 1);
@@ -414,7 +414,7 @@ namespace ImGuiNET
                     nativeTextStart = nativeTextStackBytes;
                 }
 
-                int nativeTextOffset = Util.GetUtf8(text, nativeTextStart, textByteCount, start, textToCopyLen);
+                int nativeTextOffset = Util.GetUtf8(text, start, textToCopyLen, nativeTextStart, textByteCount);
                 nativeTextStart[nativeTextOffset] = 0;
                 nativeTextEnd = nativeTextStart + nativeTextOffset;
             }

src/ImGui.NET/Util.cs

@@ -32,8 +32,10 @@ namespace ImGuiNET
         }
 
         internal static byte* Allocate(int byteCount) => (byte*)Marshal.AllocHGlobal(byteCount);
+
         internal static void Free(byte* ptr) => Marshal.FreeHGlobal((IntPtr)ptr);
-        internal static int CalcUtf8(string s, int start, int length)
+
+        internal static int CalcSizeInUtf8(string s, int start, int length)
         {
             if (start > s.Length - 1 || length > s.Length || start + length > s.Length)
             {
@@ -54,7 +56,7 @@ namespace ImGuiNET
             }
         }
 
-        internal static int GetUtf8(string s, byte* utf8Bytes, int utf8ByteCount, int start = 0, int length = 0)
+        internal static int GetUtf8(string s, int start, int length, byte* utf8Bytes, int utf8ByteCount)
         {
             fixed (char* utf16Ptr = s)
             {