To see the current tabbing order of your controls, click Order/Group from the Arrange menu. This displays the Order/Group dialog box. All controls in your new dialog are listed in the list box in their current tabbing order, which is the order in which you created them.
If this dialog box were opened in an application, by default the focus would begin with the first control you created, the OK button. The user would probably prefer that the focus begin at the list box.