For the record, so do I. Better IMHO than the default blue for "ticked" items in Hildon. Any idea how to apply that globally?
EDIT: Twice did I accidentally close the application when I was just trying to back off from a dialog, because instead of the Cancel button I instinctively clicked in the top right corner where the back arrow usually is - except that there was the X to close the whole app. This is kinda inconsistent with all the other applications.