/// <summary>
/// Get the insertion position index of the caret.
/// </summary>
private static int GetCaretIndex(TextSelection selection)
{
if (selection == null)
{
return(0);
}
var tTextRange = selection.GetType().GetInterfaces().FirstOrDefault(i => i.Name == "ITextRange");
var oStart = tTextRange?.GetProperty("Start")?.GetGetMethod()?.Invoke(selection, null);
var value = oStart?.GetType().GetProperty("Offset", BindingFlags.NonPublic | BindingFlags.Instance)?.GetValue(oStart, null) as int?;
return(value.GetValueOrDefault(0));
}