save and restore dc state

src/ddsurface.c

@@ -914,6 +914,8 @@ HRESULT dds_GetDC(IDirectDrawSurfaceImpl* This, HDC FAR* lpHDC)
     if (lpHDC)
         *lpHDC = dc;
 
+    InterlockedExchange(&This->dc_state, SaveDC(dc));
+
     return DD_OK;
 }
 
@@ -1024,6 +1026,8 @@ HRESULT dds_ReleaseDC(IDirectDrawSurfaceImpl* This, HDC hDC)
         }
     }
 
+    RestoreDC(hDC, InterlockedExchangeAdd((LONG*)&This->dc_state, 0));
+
     return DD_OK;
 }