First baby step to a restructured app_server:

- introduced new ScreenManager and VirtualScreen classes
- removed screen handling from RootLayer
- removed multiple screen/root layer stuff from Desktop, it's
  now using a VirtualScreen object instead


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@13686 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/servers/app/AppServer.cpp

@@ -31,6 +31,7 @@
 #include "RegistrarDefs.h"
 #include "RGBColor.h"
 #include "RootLayer.h"
+#include "ScreenManager.h"
 #include "ServerApp.h"
 #include "ServerCursor.h"
 #include "ServerProtocol.h"
@@ -165,6 +166,8 @@ AppServer::AppServer() :
 	if (LoadColorSet(SERVER_SETTINGS_DIR COLOR_SETTINGS_NAME, &gGUIColorSet) != B_OK)
 		gGUIColorSet.SetToDefaults();
 
+	gScreenManager = new ScreenManager();
+
 	// Set up the Desktop
 	gDesktop = new Desktop();
 	gDesktop->Init();