Unless there is some compelling reason that I am not aware of, the following *.bak files should be "hg rm"ed from the rt repo:

apps/experiments/Modena/src/modena/CombinationTest.fxml.bak
apps/experiments/Modena/src/modena/SameHeightTest.fxml.bak
apps/experiments/Modena/src/modena/simple-window.fxml.bak
apps/experiments/Modena/src/modena/ui-mosaic.fxml.bak