The Tab order of objects in windows on the XL screen is determined by the reverse order of when they are added to the window. The last object added receives focus and the object added just prior to that will be the next object to receive focus.

Combo Boxes failed to adhere to that rule, which messed up the tab order of some windows that selectively display combo boxes instead of integer prompts. The reason being that the combo box is built with a Window control and Window controls by default don't adhere to the same tab order rules. This was rectified in the Combo Box control.