Controlling User Navigation

In Navigation Services 2.0 and later, you can block certain user navigation actions such as file opening and saving by passing the kNavCtlSetActionState constant in the selector parameter of the function and one or more of the values defined by the NavActionState enumeration (described in ) in the parms parameter. This is useful when you want to prevent a dialog box from being dismissed until certain conditions are met, for example.

The actions you can block include:

Opening files

Saving files

Choosing file objects

Creating new folders

In the following example, the kNavDontOpenState constant is used to disable the Open button in an Open dialog box:

NavCustomControl( context, kNavCtlSetActionState, kNavDontOpenState );

In the next example, the kNavDontChooseState constant is used in addition to the kNavDontOpenState constant. During a call to the function, for example, this disables the Open and Choose buttons:

NavCustomControl( context, kNavCtlSetActionState, kNavDontOpenState +
                 kNavDontChooseState);

In the final example, we add the kNavDontNewFolderState constant to disable the Open, Choose, and New Folder buttons during a call to the function:

NavCustomControl( context, kNavCtlSetActionState, kNavDontOpenState +
                 kNavDontChooseState + kNavDontNewFolderState );

If you block a user action by passing one or more of the NavActionState constants, make sure you set the kNavNormalState constant before exiting in order to restore the default state. If you fail to set the kNavNormalState constant, the user may be unable to dismiss the dialog box.