The system provides a special keyboard interface for dialog boxes that carries out special processing for several keys. The interface generates messages that correspond to certain buttons in the dialog box or changes the input focus from one control to another. Following are the keys used in this interface and their respective actions.
| Key | Action |
|---|---|
| alt+mnemonic | Moves the input focus to the first control (having the WS_TABSTOP style) after the static control containing the given mnemonic. |
| down | Moves the input focus to the next control in the group. |
| enter | Sends a WM_COMMAND message to the dialog box procedure. The wParam parameter is set to IDOK or control identifier of the default push button. |
| esc | Sends a WM_COMMAND message to the dialog box procedure. The wParam parameter is set to IDCANCEL. |
| left | Moves the input focus to the previous control in the group. |
| mnemonic | Moves the input focus to the first control (having the WS_TABSTOP style) after the static control containing the given mnemonic. |
| right | Moves the input focus to the next control in the group. |
| shift+tab | Moves the input focus to the previous control that has the WS_TABSTOP style. |
| tab | Moves the input focus to the next control that has the WS_TABSTOP style. |
| up | Moves the input focus to the previous control in the group. |
The system automatically provides the keyboard interface for all modal dialog boxes. It does not provide the interface for modeless dialog boxes unless the application calls the IsDialogMessage function to filter messages in its main message loop. This means that the application must pass the message to IsDialogMessage immediately after retrieving the message from the message queue. The function processes the messages if it is for the dialog box and returns a nonzero value to indicate that the message has been processed and must not be passed to the TranslateMessage or DispatchMessage function.
Because the dialog box keyboard interface uses direction keys to move between controls in a dialog box, an application cannot use these keys to scroll the contents of any modal dialog box or any modeless dialog box for which IsDialogMessage is called. When a dialog box has scroll bars, the application must provide an alternate keyboard interface for the scroll bars. Note that the mouse interface for scrolling is available when the system includes a mouse.