user32/tests: Add a test to show that released cache DCs are disabled.

dlls/user32/tests/dce.c

@@ -110,6 +110,12 @@ static void test_dc_attributes(void)
     }
     while (i > 0) ReleaseDC( hwnd_cache, hdcs[--i] );
 
+    /* Released cache DCs are 'disabled' */
+    rop = SetROP2( old_hdc, R2_BLACK );
+    todo_wine ok( rop == 0, "got %d\n", rop );
+    rop = GetROP2( old_hdc );
+    todo_wine ok( rop == 0, "got %d\n", rop );
+
     /* test own DC */
 
     hdc = GetDC( hwnd_owndc );