Directing mouse events [DllImport("user32.dll")] click, double click

[DllImport("user32.dll", CharSet = CharSet.Auto, CallingConvention = CallingConvention.StdCall)]
public static extern void mouse_event(uint dwFlags, uint dx, uint dy, uint cButtons, UIntPtr dwExtraInfo);
private const uint MOUSEEVENTF_LEFTDOWN = 0x02;
private const uint MOUSEEVENTF_LEFTUP = 0x04;
private const uint MOUSEEVENTF_RIGHTDOWN = 0x08;
private const uint MOUSEEVENTF_RIGHTUP = 0x10;

You should Import and Define these Constant's to work with Mouse using Win32API

Use method's below to do Mouse Operation's

void sendMouseRightclick(Point p)
{
    mouse_event(MOUSEEVENTF_RIGHTDOWN | MOUSEEVENTF_RIGHTUP, p.X, p.Y, 0, 0);
}

void sendMouseDoubleClick(Point p)
{
    mouse_event(MOUSEEVENTF_LEFTDOWN | MOUSEEVENTF_LEFTUP, p.X, p.Y, 0, 0);

Thread.Sleep(150);

    mouse_event(MOUSEEVENTF_LEFTDOWN | MOUSEEVENTF_LEFTUP, p.X, p.Y, 0, 0);
}

void sendMouseRightDoubleClick(Point p)
{
    mouse_event(MOUSEEVENTF_RIGHTDOWN | MOUSEEVENTF_RIGHTUP, p.X, p.Y, 0, 0);

    Thread.Sleep(150);

    mouse_event(MOUSEEVENTF_RIGHTDOWN | MOUSEEVENTF_RIGHTUP, p.X, p.Y, 0, 0);
}

void sendMouseDown()
{
    mouse_event(MOUSEEVENTF_LEFTDOWN, 50, 50, 0, 0);
}

void sendMouseUp()
{
    mouse_event(MOUSEEVENTF_LEFTUP, 50, 50, 0, 0);
}

If you want to do a Mouse Drag you should First Send MouseDown(Mouse Click) and keep it Clicked While Changing the Mouse Position than Send MouseUp(Release Click) something like this .

sendMouseDown();
Cursor.Position = new Point(30,30);
sendMouseUp();

Using long type raises an "PInvoke" error.

We should use int type:

[DllImport("user32.dll")]
static extern void mouse_event(int dwFlags, int dx, int dy, 
                      int dwData, int dwExtraInfo);

[Flags]
public enum MouseEventFlags
{
    LEFTDOWN = 0x00000002,
    LEFTUP = 0x00000004,
    MIDDLEDOWN = 0x00000020,
    MIDDLEUP = 0x00000040,
    MOVE = 0x00000001,
    ABSOLUTE = 0x00008000,
    RIGHTDOWN = 0x00000008,
    RIGHTUP = 0x00000010
}

public static void LeftClick(int x, int y)
{
    Cursor.Position = new System.Drawing.Point(x, y);
    mouse_event((int)(MouseEventFlags.LEFTDOWN), 0, 0, 0, 0);
    mouse_event((int)(MouseEventFlags.LEFTUP), 0, 0, 0, 0);
}

source: http://www.pinvoke.net/default.aspx/user32.mouse_event

Take a look at pinvoke.net for a listing of the available APIs. Code examples and the import statements are included. You can also expand the selection on the left to see the available APIs for each DLL.