Game Programming using Qt 5 Beginner's Guide

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The tab order

While you're previewing the form, you can check another aspect of the UI design. Note which line edit receives the focus when the form is open. There is a chance that the second line edit will be activated first. To check and modify the order of focus, close the preview and switch to the tab order editing mode by clicking on the icon called Edit Tab Order in the toolbar.

This mode associates a box with a number to each focusable widget. By clicking on the rectangle in the order you wish the widgets to gain focus, you can reorder values, thus re-ordering focus. Now make it so that the order is as shown here:

Our form only has two widgets that can receive focus (except for the dialog's buttons, but their tab order is managed automatically). If you create a form with multiple controls, there is a good chance that when you press the Tab key repeatedly, the focus will start jumping back and forth between buttons and line edits instead of a linear progress from top to bottom (which is an intuitive order for this particular dialog). You can use this mode to correct the tab order.

Enter the preview again and check whether the focus changes according to what you've set.

When deciding about the tab order, it is good to consider which fields in the dialog are mandatory and which are optional. It is a good idea to allow the user to tab through all the mandatory fields first, then to the dialog confirmation button (for example, one that says OK or Accept), and then cycle through all the optional fields. Thanks to this, the user will be able to quickly fill all the mandatory fields and accept the dialog without the need to cycle through all the optional fields that the user wants to leave as their default values.