Now open an Interface communication channel with a DIALOG OPEN command, and grab the address of the first character in the item array to be loaded into an Interface variable.
X> Dialog Open A$,1 AD=Array(ITEM(0)) : Vdialog(1,0)=AD
Finally, call the Interface program with DIALOG RUN, like this:
X> R=Dialog Run(1)
Creating a selector
The ActiveList command is very useful, but it is not intended to operate in isolation. To create a
working selection box, an appropriate set of sliders, buttons and edit zones need to be linked up,
as explained in the next part of this Chapter.
ZonePosition
Interface function: return the status of a zone
value=ZP
ZonePosition returns the value of the current zone's status. In fact it is simply an expanded version of the BP function, with the difference being that it can be used in any active zone, including buttons.
ZoneChange
Interface instruction: change the status of a zone
ZC zone number,new data;
ZoneChange is a simple expansion of the BC instruction. It is used within the "changes" square brackets to link a number of zones together into one compound object. After the ZC command, specify the number of the zone to be affected, followed by some new data that is to be fed into the zone.
The new data depends on the type of zone that is to be affected, and there are four possibilities:
Buttons. The data holds a new value for the status of the button position. If this is different from the current position, the button will be re-drawn immediately.
Edit zones. If a text zone has been created with EDit, the new data should contain a new string of characters that is to be displayed in the box. Similarly, if the zone was defined using Digit, the existing number will be replaced by a newly specified value.
Sliders. The data is used to move the slider bar on the screen, exactly as if it had been selected by the user.
Active lists. In this case, the selection window is scrolled up or down the string array.