If a Rebar window is altered by calling either ShowWindow() or UpdateWindow() then we were only updating the parent and omitting their children windows. This is closer to the behavior of the very very old SVN r27394 == git f1a7f30 . And therefore intentionally excludes parts of SVN r27403 == git e2651a0 . The bots have no complaints about it: KVM https://reactos.org/testman/compare.php?ids=81266,81290 VBox https://reactos.org/testman/compare.php?ids=81267,81291