This section allows you to define which keys your readers may use to navigate through your publication. You may wish to activate some of these key options for those users who do not have a mouse, or simply for the convenience of your readers. The Keyboard Control options are described below:


Allow ESC key to exit publication: Disable this option to prevent your readers from closing your publication by pressing the Esc key. If you disable this feature, be sure to provide your readers with another way to shut down your publication, such as an exit button.


Allow Page Up, Page Down, Home and End keys to change pages: Enable this option to allow your readers to move about your publication using these keys. In some situations, you may want to disable these keys in order to control which pages readers can visit and in what order. Many authors choose to disable these keys and instead provide a set of navigation buttons. Unlike the keyboard method, navigation buttons can include Action commands to intelligently determine if changing pages is OK. For example, a publication designed to administer a classroom quiz could make sure that an answer has been selected before allowing the student to move on to the next topic.


Display visible marquee to indicate item with keyboard focus: For publications that include text entry fields, check boxes and other input devices, enabling this option will allow the reader to access these items by pressing the keyboard’s Tab key. The active object will be surrounded by a rectangle, or marquee, indicating that it has the input focus. See Arrange > Set Tab Order to specify the order in which objects will be selected.


Disable Ctrl+Alt+Del and Alt+Tab keys: This option allows you to prevent readers from switching to other programs (Alt+Tab) or using the Crtl+Alt+Del key combination to shut down your publication. This option is intended only for use with special types of publications, like kiosks, where it can be disastrous to allow the reader unrestricted access to the computer. It’s generally unwise for normal Windows programs to disallow access to these functions. This feature is not available in Windows Vista.


Disable Print Screen key: This option will prevent readers from using the Print Screen key to copy images from your publication's screen to the Windows clipboard. There are other methods that can be used to copy screen images, so this option will not prevent someone intent on stealing images. The Print Screen key is the most common method of capturing screen images, so disabling it is helpful.


Note: It's not possible to disable both Ctrl+Alt+Del and Print Screen under Windows 95, 98 or ME. If both these options are selected when running this publication under Windows 95, 98 or ME, then only Print Screen will be disabled. This problem does not affect Windows NT, 2000 or XP.


Prevent multiple copies of this publication from running at the same time: Enable this option to prevent more than one copy of your publication from running at the same time. This is a good idea for most publications, since multiple instances of the same program waste system resources and can confuse users.


You can detect when a user attempts to launch a second instance of your publication by creating a special subroutine called CommandLine_OnChange. VisualNEO Win will automatically execute this subroutine whenever the user attempts to start more than one copy of your publication. For example:


:CommandLine_OnChange

  AlertBox "Warning" "An attempt was made to launch a second copy of this app."

Return


The CommandLine_OnChange subroutine is particularly useful if your publication uses the global [CommandLine] variable to load external files at startup. Prior to executing CommandLine_OnChange, VisualNEO Win will automatically update the contents of the [CommandLine] variable with the command line of the second instance. This is useful if you have registered a file type association with Windows, which allows users to start your publication by double clicking on a file matching the association. Windows passes the name of clicked file to your publication via the command line which you can intercept using the [CommandLine] variable.


See App Properties > Actions for more information on creating subroutines.


Note: The CommandLine_OnChange subroutine will not be executed unless the Prevent Multiple Copies... option is enabled.


Disabling the Display error messages option allows advanced VisualNEO Win authors to trap and respond to errors programmatically rather than having VisualNEO Win display the error in a dialog box. When this option is off, all error messages are placed in the global [LastError] variable. You can use this variable in your Action scripts to determine when an error occurs and respond appropriately. For example:


FileWrite "parts.dat" "Append" "[PartNum], [Desc], [Price]"

If "[LastError]" ">" ""

  AlertBox "Error" "Unable to write data to Parts.dat!"

EndIf


You can turn the error display on and off programmatically using the ShowErrors Action.


Turning off the Display the Windows print setup screen for all print actions will disable the Print Setup screen, causing actions that use the printer (PrintPage, PrintTextFile, etc.) to begin printing without first asking for confirmation. When this feature is off, the Print Setup screen can still be accessed manually using the PrintSetup Action. For example:


PrintSetup "[Result]"

If "[Result]" "=" "True"

  PrintPage "Contents"

  PrintPage "Help"

EndIf


Enabling the Automatically update objects containing time sensitive variables option instructs VisualNEO Win to update the screen at regular intervals. This is useful if your publication contains objects which display the current time or date. If this option is turned off, these objects will only be updated when entering or leaving a page.


The Image Cache Size may be adjusted to optimize the performance of publications that contain a large number of images. For publications with many small images, you may be able to improve performance by increasing the size of the cache. For publications that consist primarily of very large images, performance can be improved by reducing the cache size. Incorrectly adjusting the cache size can have the opposite effect and actually degrade performance, especially on older PCs. For this reason we recommend that you leave the cache size set at the default value of 30 unless you're having performance problems.