Windows: SetCursorPos over RDP sometimes results in wrong position - windows

Question

I am connected to a Windows VM via RDP. The host system is also Windows. On the VM, I run an application that uses SetCursorPos to change the position of the mouse cursor. I have observed that the call sometimes causes the mouse cursor to arrive at a completely different location.
If I run the application on the host system, it runs without errors. So it seems to be related to RDP.
Consider the following C# demo application. Basically, it calls SetCursorPos a thousand times with random positions and checks with GetCursorPos whether the mouse cursor has landed at the specified position.
using System;
using System.Runtime.InteropServices;
using System.Threading;
namespace CursorDemoApp
{
class Program
{
static void Main()
{
var random = new Random(1);
var displayWidth = GetDisplayWidth();
var displayHeight = GetDisplayHeight();
for (var run = 1; run <= 1000; run++)
{
SetAndCheckCursorPosition(0, 0);
var x = random.Next(displayWidth);
var y = random.Next(displayHeight);
SetAndCheckCursorPosition(x, y);
Thread.Sleep(10);
}
}
private static void SetAndCheckCursorPosition(int x, int y)
{
SetCursorPosition(x, y);
var currentPosition = GetCursorPosition();
if (currentPosition.X != x || currentPosition.Y != y)
{
Console.WriteLine("Failed! Expected: ({0},{1}) - Got: ({2},{3})", x, y, currentPosition.X, currentPosition.Y);
}
}
private static void SetCursorPosition(int x, int y)
{
Console.WriteLine("SetCursorPosition({0},{1})", x, y);
SetCursorPos(x, y);
}
[DllImport("user32.dll")]
private static extern bool SetCursorPos(int x, int y);
private static Point GetCursorPosition()
{
GetCursorPos(out var point);
Console.WriteLine("GetCursorPosition() == ({0},{1})", point.X, point.Y);
return point;
}
[DllImport("user32.dll")]
private static extern bool GetCursorPos(out Point point);
private static int GetDisplayWidth()
{
return GetSystemMetrics(16 /* SM_CXFULLSCREEN */);
}
private static int GetDisplayHeight()
{
return GetSystemMetrics(17 /* SM_CYFULLSCREEN */);
}
[DllImport("user32.dll")]
private static extern int GetSystemMetrics(int index);
[StructLayout(LayoutKind.Sequential)]
private struct Point
{
public int X;
public int Y;
}
}
}
When I run this in the VM, I get as output, for example:
...
SetCursorPosition(0,0)
GetCursorPosition() == (0,0)
SetCursorPosition(1330,269)
GetCursorPosition() == (1330,269)
SetCursorPosition(0,0)
GetCursorPosition() == (0,0)
SetCursorPosition(18,10)
GetCursorPosition() == (1330,269)
Failed! Expected: (18,10) - Got: (1330,269)
SetCursorPosition(0,0)
GetCursorPosition() == (0,0)
SetCursorPosition(973,392)
GetCursorPosition() == (973,392)
...
Can anyone explain this behavior or provide a solution?
(Originally, I noticed this when using Eclipse SWT and Display.setCursorLocation(..). Since that also uses SetCursorPos under the hood, I wanted to leave this as a hint for search engines.)

Answer 1

Faced the same problem. Googling "SetCursorPos RDP" leads to older question:
SetCursorPos not working over remote desktop (reading from WM_INPUT event)
raffallo provided an answer, SO requires me to cite it:
It's a really old thread, but in the current world situation, it might be helpful.
To fix problems with RDP and mouse you need to open Local Group Policy Editor and go to:
Local Computer Policy > Computer Configuration > Administrative Templates > Windows Components > Remote Desktop Services > Remote Desktop Session Host > Remote Session Environment.
In the Remote Session Environment you need to set Use WDDM graphic display driver for Remote Desktop Connections to disable.
Probably Windows 10 Pro is required, but I can't check it.
This change you need to make in the machine you want to connect to (host).
Restarting Windows is recommended.