[PATCH 1/1] win32u: Query virtual desktop status from the registry.

[Zhiyi Zhang]

From: Zhiyi Zhang

Checking flags of the thread desktop to determine whether virtual desktop is on is unreliable.
For example, CEF applications create their own desktop and so is_virtual_desktop() could incorrectly
report that virtual desktop is off.

Wine-Bug: https://bugs.winehq.org/show_bug.cgi?id=55810
---
 dlls/win32u/winstation.c    | 20 +++++++++++++++-----
 programs/explorer/desktop.c | 24 +++++++++++++++++++++++-
 2 files changed, 38 insertions(+), 6 deletions(-)

diff --git a/dlls/win32u/winstation.c b/dlls/win32u/winstation.c
index b187b246941..249ea922f28 100644
--- a/dlls/win32u/winstation.c
+++ b/dlls/win32u/winstation.c
@@ -42,12 +42,22 @@ WINE_DECLARE_DEBUG_CHANNEL(win);

BOOL is_virtual_desktop(void)
 {
-    HANDLE desktop = NtUserGetThreadDesktop( GetCurrentThreadId() );
-    USEROBJECTFLAGS flags = {0};
-    DWORD len;
+    static const WCHAR enabledW[] = {'E','n','a','b','l','e','d',0};
+    static int enabled = -1;
+    char value_buffer[FIELD_OFFSET(KEY_VALUE_PARTIAL_INFORMATION, Data[40 * sizeof(WCHAR)])];
+    KEY_VALUE_PARTIAL_INFORMATION *info = (void *)value_buffer;
+    DWORD size;
+    HKEY key;
+
+    if (enabled == -1 && (key = reg_open_hkcu_key( "Software\Wine\Explorer\VirtualDesktop" )))
+    {
+        size = query_reg_value( key, enabledW, info, sizeof(value_buffer) );
+        if (size == sizeof(DWORD) && info->Type == REG_DWORD)
+            enabled = *(DWORD *)info->Data > 0;
+        NtClose( key );
+    }

-    if (!NtUserGetObjectInformation( desktop, UOI_FLAGS, &flags, sizeof(flags), &len )) return FALSE;
-    return !!(flags.dwFlags & DF_WINE_CREATE_DESKTOP);
+    return enabled > 0;
 }

/***********************************************************************
diff --git a/programs/explorer/desktop.c b/programs/explorer/desktop.c
index 9a58f13d887..923e5c27bb0 100644
--- a/programs/explorer/desktop.c
+++ b/programs/explorer/desktop.c
@@ -973,6 +973,21 @@ static void initialize_display_settings( unsigned int width, unsigned int height
     }
 }

+static void save_virtual_desktop_settings( DWORD enabled )
+{
+    LSTATUS ls;
+    HKEY hkey;
+
+    /* Store virtual desktop status at HKCU\Software\Wine\Explorer\VirtualDesktop */
+    ls = RegCreateKeyExW( HKEY_CURRENT_USER, L"Software\Wine\Explorer\VirtualDesktop", 0, NULL,
+                          REG_OPTION_VOLATILE, KEY_ALL_ACCESS, NULL, &hkey, NULL );
+    if (!ls)
+    {
+        RegSetValueExW( hkey, L"Enabled", 0, REG_DWORD, (BYTE *)&enabled, sizeof(enabled) );
+        RegCloseKey( hkey );
+    }
+}
+
 static void set_desktop_window_title( HWND hwnd, const WCHAR *name )
 {
     static const WCHAR desktop_nameW[] = L"Wine desktop";
@@ -1065,7 +1080,10 @@ void manage_desktop( WCHAR *arg )
     {
         DEVMODEW devmode = {.dmPelsWidth = width, .dmPelsHeight = height};
         /* magic: desktop "root" means use the root window */
-        if ((using_root = !wcsicmp( name, L"root" ))) desktop = CreateDesktopW( name, NULL, NULL, 0, DESKTOP_ALL_ACCESS, NULL );
+        using_root = !wcsicmp( name, L"root" );
+        /* save virtual desktop status to the registry before creating desktops */
+        save_virtual_desktop_settings( !using_root );
+        if (using_root) desktop = CreateDesktopW( name, NULL, NULL, 0, DESKTOP_ALL_ACCESS, NULL );
         else desktop = CreateDesktopW( name, NULL, &devmode, DF_WINE_CREATE_DESKTOP, DESKTOP_ALL_ACCESS, NULL );
         if (!desktop)
         {
@@ -1074,6 +1092,10 @@ void manage_desktop( WCHAR *arg )
         }
         SetThreadDesktop( desktop );
     }
+    else
+    {
+        save_virtual_desktop_settings( FALSE );
+    }

/* create the desktop window */
     hwnd = CreateWindowExW( 0, DESKTOP_CLASS_ATOM, NULL,