Windows App Certification Kit fails: Multi user session test

Question

I'm trying to pull a WinForms application through the Windows App Certification Kit and gets a fail on this test:

  <TEST INDEX="17" NAME="Multi user session test" DESCRIPTION="Multi User checks Application invocation in multiple sessions." EXECUTIONTIME="00h:00m:24s.22ms">
  <RESULT><![CDATA[FAIL]]></RESULT>
  <MESSAGES />

I guess that this is because I only allow one instance of the application to run, like this:

using ( var p = System.Diagnostics.Process.GetCurrentProcess() )
if ( System.Diagnostics.Process.GetProcessesByName( p.ProcessName ).Length > 1 )
{
    MessageBox.Show(
            "An instance of xxx is already running!",
            Title,
            MessageBoxButtons.OK,
            MessageBoxIcon.Exclamation );
    return;
 }

It is a tray-application activated by a hot-key combination, registered with this function:

[DllImport( "user32", EntryPoint = "RegisterHotKey", CharSet = CharSet.Ansi, SetLastError = true, ExactSpelling = true )]
public static extern int RegisterHotkey( IntPtr hWnd, int id, int fsModifiers, int vk );

So I guess I have two questions:

1) How can I correctly prevent multiple sessions being run within the same user session but allow several instances across multiple user sessions?

2) Will I be able to register the same hot-key in different user sessions? Or must I somehow unregister and re-register the hot-key when user sessions are switched?

TIA

Answer 1

You can achieve the same effect using a Mutex. See MSDN for details, but the short version is that any mutex created with a name starting with "Local\" will be per-session. Enter a mutex named "Local\MyAppName" and only one instance of your app can run per-session.

Hotkeys are registered per-session and it will not be a problem to register the same hotkey in multiple sessions.

Example Use (from Run single instance of an application using Mutex):

bool ownsMutex = false;
// NOTE: Local is the default namespace, so the name could be shortened to myApp
Mutex myMutex = new Mutex(false, @"Local\myApp");

try 
{
    ownsMutex = myMutex.WaitOne(0)
}
catch (AbandonedMutexException)
{
    ownsMutex = true;
}

if (!ownsMutex)
{
    MessageBox.Show("myApp is already running!", "Multiple Instances");
    return;
}
else 
{
    try 
    {
        Application.Run(new Form1());
    }
    finally 
    {
        myMutex.ReleaseMutex();
    }
}