explorer: Set virtual desktop primary adapter display settings.

programs/explorer/desktop.c

@@ -937,10 +937,10 @@ static const char *debugstr_devmodew( const DEVMODEW *devmode )
                              position );
 }
 
-static void initialize_display_settings(void)
+static void initialize_display_settings( unsigned int width, unsigned int height )
 {
     DISPLAY_DEVICEW device = {.cb = sizeof(DISPLAY_DEVICEW)};
-    DWORD i = 0;
+    DWORD i = 0, flags = CDS_GLOBAL | CDS_UPDATEREGISTRY;
 
     /* Store current display mode in the registry */
     while (EnumDisplayDevicesW( NULL, i++, &device, 0 ))
@@ -955,10 +955,24 @@ static void initialize_display_settings(void)
 
         TRACE( "Device %s current display mode %s.\n", debugstr_w( device.DeviceName ), debugstr_devmodew( &devmode ) );
 
-        if (ChangeDisplaySettingsExW( device.DeviceName, &devmode, 0,
-                                      CDS_GLOBAL | CDS_NORESET | CDS_UPDATEREGISTRY, 0 ))
+        if (ChangeDisplaySettingsExW( device.DeviceName, &devmode, 0, flags | CDS_NORESET, 0 ))
             ERR( "Failed to initialize registry display settings for %s.\n", debugstr_w( device.DeviceName ) );
     }
+
+    if (!using_root)
+    {
+        DEVMODEW devmode =
+        {
+            .dmSize = sizeof(DEVMODEW),
+            .dmFields = DM_PELSWIDTH | DM_PELSHEIGHT,
+            .dmPelsWidth = width,
+            .dmPelsHeight = height,
+        };
+
+        /* in virtual desktop mode, set the primary display settings to match desktop size */
+        if (ChangeDisplaySettingsExW( NULL, &devmode, 0, flags, NULL ))
+            ERR( "Failed to set primary display settings.\n" );
+    }
 }
 
 static void set_desktop_window_title( HWND hwnd, const WCHAR *name )
@@ -1085,7 +1099,7 @@ void manage_desktop( WCHAR *arg )
         if (thread) CloseHandle( thread );
         SystemParametersInfoW( SPI_SETDESKWALLPAPER, 0, NULL, FALSE );
         ClipCursor( NULL );
-        initialize_display_settings();
+        initialize_display_settings( width, height );
         initialize_appbar();
 
         if (using_root) enable_shell = FALSE;