The application can control the focus using the functions IupGetFocus and IupSetFocus. When the focus is changed the application is notified trough the callbacks GETFOCUS_CB and KILLFOCUS_CB.
Keyboard navigation in the dialog uses the "Tab" and "Shilf+Tab" keys to change the keyboard focus from one control to another. The exception is when the focus is at an IupMultiline control, to change focus the combination "Ctrl+Tab" must be used, because "Tab" is a valid input for the text. All IUP interactive controls have Tab stops, but the navigation order is related to the order the controls are placed in the dialog and can not be changed. The order is the same implemented by the functions IupNextField and IupPreviousField. To remove the Tab stop from a control use the CANFOCUS attribute.
Arrows can also be used for navigation between buttons and toggles. This is necessary because when an IupToggle is inside an IupRadio the "Tab" keys will navigate only to the selected toggle.
In Windows, the focus feedback only appears after the user presses a key (except for the IupText where the feedback is the caret). Before pressing a key if you click in a control the focus feedback will be NOT be shown although it will be in focus. IupMatrix and other additional controls will always show their focus feedback. In GTK and Motif the focus feedback is always shown for the control that has the focus.
Two keys are also important in keyboard navigation: "Enter" and "Esc". But they are only effective if the application register the attributes DEFAULTENTER and DEFAULTESC of the IupDialog. These attributes configure buttons to be activated when the respective key is pressed. Again "Enter" is a valid key for the Multiline so the combination "Ctrl+Enter" must be used instead. If the focus is at a button then the Enter key will activate that button independent from the DEFAULTENTER attribute.
Usualy the application will process keyboard input in the IupCanvas using the KEYPRESS_CB callback. But there is also the K_ANY callback that can be used for all the controls, but it does not have control of the press state, it is called only when the key is pressed. Both callbacks use the key codification explained in Keyboard Codes. These codes are also used in the ACTION callbacks of IupText and IupMultiline, and in shortcuts using the KEY attribute of IupItem and IupSubmenu. Finally all the keyboard codes can be used as callback names to implement application hot keys.