Tab order refers to the relative order of controls in a dialog when you move from one to the next by pressing the Tab key. It’s also known as z-order (based on the controls' relative positions on a theoretical z-axis).

Tab order is also important when you have a static text control that acts as a label for another control (e.g. an edit control). A mnemonic assigned to the static text control (via a & in its label) will activate the control immediately following it in the tab order.

When you add a new control to a dialog it automatically takes a position after all existing controls in the tab order, but you can modify the order of existing controls using the Tab order command (  ).

The Tab order command is modal – click the button once to turn it on, and again to turn it off. When this mode is enabled all controls will display their current position in the tab order. To re-order controls, click the control you want to be first (number 1) in the tab order, then the second control, then the third, and so on. If most controls are already correct and you just want to modify one or two, hold the Shift key down and click the control immediately before the first one that you want to modify – then continue clicking controls to reorder them as normal.