Define icon triggers

The action of pressing a mouse button while pointing to an icon is called an icon trigger, because it triggers an action associated with the icon. ``Icon triggers'' shows the default icon triggers.

Icon triggers

User	Mouse	Trigger	Object script	Used for
action	button	type	file name
double-click	1	static	activate	start
double-click	2	static	alt_activate	alternate start
hold down	3	hold	menu	pop-up menu
drag and drop	1	drop	drop	start on file
drag and drop	2	drop	drop	start on file
drag and drop	<Ctrl> 1	drop	alt_drop	alternate start on file
drag and drop	<Ctrl>	2	drop	alt_drop
alternate start on file

On a three-button mouse, the buttons are referred to as mouse buttons 1, 2 and 3. Mouse buttons 1 (the left button by default) and 3 (the right button by default) can be swapped to accommodate left-handed users. On a two-button mouse, users can simulate button 2 by pressing both buttons simultaneously. For more about how a mouse is used, see Using the Desktop.

To define an icon trigger:

1. Write a Deskshell object script for each trigger you want to define.

   You should only define actions for the triggers listed in ``Icon triggers''. Other user manipulations of your icon (single-clicking on it or dragging it to a new location, for example) are handled automatically. Sample object scripts for activate, drop, and menu triggers are presented on the following pages.

   The activate trigger must be used to start your application. By default, double-clicking with mouse button 2 (the alt_activate trigger) brings up a a dialog box that prompts the user for command line options to the startup command in your activate script. Similarly, a file icon dragged with mouse button 3 and dropped on your icon (the d3 trigger) brings up a prompt for startup options, then executes your script for the drop trigger.

   Use the Deskshell command language to write object scripts. It provides the same basic functions as the Bourne shell, along with additional commands for defining special Desktop actions. Instructions for using Deskshell are in the chapter ``Writing scripts in Deskshell'' in the Graphical Environment Guide.

   Only write object scripts for those triggers that are relevant to your application. For example, an application that simply displays a clock does not need to define what happens when a text file is dropped on it. If a trigger is not defined with an object script, a message will notify the user that the action (double-click, hold, or drop) is not defined for that button.

   You can use a similar application's trigger files as templates for yours, by copying them to the desired filenames. In doing so, you will include default rules for 2-state animation.
   

2. Name each object script file as specified in Table 2.