creating a new project with a single RadWindow will cause the window control buttons (close, maximise, minimise) to shift to the right when restored from minimised, resulting in the close button being pushed off the visible space at any size:

when RadWindowInteropHelper.ShowInTaskbar="True" is used the problem does not occur.

a replication project is attached but the Telerik assembly references will probably need to be reset (I tested back until 2021.1.1x release).