As discussed in Graphical Objects, Image Regions, and Sense Regions, the user selects an object to invoke the response to OBJECT definition.

 

For example:

 

response to NewText

    make NewText background green

 

The senseport (selectable area) of a textual region is the space within, and including, its border.

 

You can use the xcoord and ycoord response inquiry built-in functions to ask ESL for the exact position of a selection; these functions return the column and line number of the point selected. For example, if a textual region is being used to display a menu of items, with each item on a new line, ycoord can allow you to determine which item was selected. (See Graphical Objects, Image Regions, and Sense Regions for a complete description of these functions.)