C# Signature:

[DllImport("user32.dll")]
static extern uint SendInput(uint nInputs, INPUT [] pInputs, int cbSize);

VB Signature:

Declare Function SendInput Lib "user32.dll" (nInputs As Integer, pInputs() As _
   INPUT, cbSize As Integer) as UInt32

User-Defined Types:

INPUT, and VK is used in the sample code.

Notes:

NB - The C# signature (and I presume the VB one as well) are inconsistent with the example code, unfortunately I don't have time to fix it right now. But if you attempt to use this, be aware that there are several inconsistencies in whether an argument is signed or unsigned between the signature and the example code.

Tips & Tricks:

Please add some!

Sample Code:

class Test
{
    void Test()
    {
    INPUT structInput;
    structInput = new INPUT();
    structInput.type = Win32Consts.INPUT_KEYBOARD;

    // Key down shift, ctrl, and/or alt
    structInput.ki.wScan = 0;
    structInput.ki.time = 0;
    structInput.ki.dwFlags = 0;
    structInput.ki.dwExtraInfo = Win32.GetMessageExtraInfo();
    if (Shift)
    {
        structInput.ki.wVk = (ushort)VK.SHIFT;
        intReturn = Win32.SendInput(1, ref structInput, (UInt32)sizeof(INPUT));
    }
    if (Ctrl)
    {
        structInput.ki.wVk = (ushort)VK.CONTROL;
        intReturn = Win32.SendInput(1, ref structInput, (UInt32)sizeof(INPUT));
    }
    if (Alt)
    {
        structInput.ki.wVk = (ushort)VK.MENU;
        intReturn = Win32.SendInput(1, ref structInput, (UInt32)sizeof(INPUT));
    }
    if (Win)
    {
        structInput.ki.wVk = (ushort)VK.LWIN;
        intReturn = Win32.SendInput(1, ref structInput, (UInt32)sizeof(INPUT));
    }
    // Key down the actual key-code
    structInput.ki.wVk = vk;
    intReturn = Win32.SendInput(1, ref structInput, (UInt32)sizeof(INPUT));
    // Key up the actual key-code
    structInput.ki.dwFlags = Win32Consts.KEYEVENTF_KEYUP;
    intReturn = Win32.SendInput(1, ref structInput, (UInt32)sizeof(INPUT));
    // Key up shift, ctrl, and/or alt
    if (Shift)
    {
        structInput.ki.wVk = (ushort)VK.SHIFT;
        intReturn = Win32.SendInput(1, ref structInput, (UInt32)sizeof(INPUT));
    }
    if (Ctrl)
    {
        structInput.ki.wVk = (ushort)VK.CONTROL;
        intReturn = Win32.SendInput(1, ref structInput, (UInt32)sizeof(INPUT));
    }
    if (Alt)
    {
        structInput.ki.wVk = (ushort)VK.MENU;
        intReturn = Win32.SendInput(1, ref structInput, (UInt32)sizeof(INPUT));
    }
    if (Win)
    {
        structInput.ki.wVk = (ushort)VK.LWIN;
        intReturn = Win32.SendInput(1, ref structInput, (UInt32)sizeof(INPUT));
    }
    }
}

Alternative Managed API:

Do you know one? Please contribute it!