C#

<br />
Popup popup = new Popup();<br />
<br />
// Get bounds of the screen on which this Application is located<br />
Rectangle screenBounds = Screen.GetBounds(this.Location);<br />
<br />
// Get scaling factor for font used (will be 1 if using small fonts, 96 fpi)<br />
float scaleY = Form.GetAutoScaleSize(this.Font).Height / 13.0f;<br />
float scaleX = Form.GetAutoScaleSize(this.Font).Width / 5.0f;<br />
<br />
// Get screen coordinates of button that opens popup<br />
Point ButtonLocation = ((Control)sender).PointToScreen(Point.Empty);<br />
int x = ButtonLocation.X;<br />
int y = ButtonLocation.Y;<br />
<br />
if( screenBounds.Bottom < (y+popup.Height) )	//Open popup up instead of down<br />
{<br />
        //make sure the whole of the popup fits on screen<br />
	if( eventButtonLocation.Y < popup.Height )<br />
		popup.Height = eventButtonLocation.Y;	<br />
<br />
	y = (eventButtonLocation.Y - popup.Height + eventLabel.Height);<br />
}<br />
<br />
if(screenBounds.Right < (x + popup.Width) )	//Open to left instead of right<br />
	x = x - popup.Width + ((Control)sender).Width;<br />
<br />
// Set location of popup<br />
popup.Location = new Point(x,y);<br />
<br />
// Add event handler<br />
popup.Closed += PopupClosedEventHandler;<br />
<br />
// Display it<br />
popup.Show();<br />

		[StructLayout(LayoutKind.Sequential)]
			public class SP_DEVICE_INTERFACE_DATA  // name doesn't matter - keep it simple
		{
			public uint cbSize;
			public Guid InterfaceClassGuid;
			public uint Flags;
			public IntPtr Reserved;
			// If you want, a helpful ctor
//			public SP_DEVICE_INTERFACE_DATA (uint cbSize, Guid InterfaceClassGuid,
//				uint Flags)
//			{
//				this.cbSize = cbSize;
//				this.InterfaceClassGuid = InterfaceClassGuid;
//				this.Flags = Flags;
//				this.Reserved = IntPtr.Zero;
//			}
		}
 
		[StructLayout(LayoutKind.Sequential, CharSet=CharSet.Auto)]
			public class SP_DEVICE_INTERFACE_DETAIL_DATA 
		{
			public uint cbSize;
			[MarshalAs(UnmanagedType.ByValTStr, SizeConst=1)]
			public string DevicePath; // Or public char DevicePath should work
		}
 
		[StructLayout(LayoutKind.Sequential)]
			public class SP_DEVINFO_DATA
		{
			// Actually, you can reuse SpDeviceInterfaceData - their declaration
			// is the same, but I'll type this out anyway...
			public uint cbSize;
			public Guid ClassGuid;
			public uint DevInst;
			public IntPtr Reserved;
		}
 
		[DllImport("setupapi.dll")]
		public static extern bool SetupDiGetDeviceInterfaceDetail(
			IntPtr DeviceInfoSet,
			ref SP_DEVICE_INTERFACE_DATA DeviceInterfaceData,
			out SP_DEVICE_INTERFACE_DETAIL_DATA DeviceInterfaceDetailData,
			uint DeviceInterfaceDetailDataSize,
			out uint RequiredSize,
			out SP_DEVINFO_DATA DeviceInfoData);

// First get size of required buffer for detailed information
Win32APIfunctions.SP_DEVICE_INTERFACE_DATA devInterfaceData = new Interfaces.Win32APIfunctions.SP_DEVICE_INTERFACE_DATA();
devInterfaceData.cbSize = (uint)Marshal.SizeOf(devInterfaceData);

Win32APIfunctions.SP_DEVICE_INTERFACE_DETAIL_DATA devInterfaceDetailData = null;

Win32APIfunctions.SP_DEVINFO_DATA devInfoData = null;

uint uiRequiredSize=0;
Win32APIfunctions.SetupDiGetDeviceInterfaceDetail(NewDeviceInfoSet, ref devInterfaceData, out devInterfaceDetailData, 0, out uiRequiredSize, out devInfoData);

int iLastError = Marshal.GetLastWin32Error();