Thanks again Lyndel,
I want to run a function 'time' recurring in the background.
That must be stable and independent.
I've created a library to run an intervalTimer every 60 seconds.
I've putted the library at system level.

/*!
@title test5.v-Fischer
@version 1.0
@author v Fischer
*/

var updateInterval = 60 * 1000; // 1 min; in msec

function getDate() {
d = new Date();
return d.getFullYear() + "-" + ("0" + Number(d.getMonth()+1)).slice(-2)+"-"+ d.getDate() + "T" + GUI.getDisplayTime() + ":" + ("0" + d.getSeconds()).slice(-2);
}

function time() {
var timePattern = new RegExp('(\\d+):(\\d+)((am|pm)*)','g');
GUI.getDisplayTime().match(timePattern);


var hour = parseInt(RegExp.$1,10);
var minute = parseInt(RegExp.$2,10);

if (hour === 3 && minute === 55) {CF.widget("A4","B","C").executeActions();}

var ampm = RegExp.$3;
var seconds = new Date().getSeconds();
}
time();

/*
schedule periodic updates for when the TSU sits in the charging dock
and it is powered on.
*/
function periodicUpdate_2(activity) {
System.setDebugMask(9);
System.print(getDate() + " [ScheduleAfter]_____TIMER");
time();
activity.scheduleAfter(updateInterval, periodicUpdate_2, activity);
}





Embedded is a function 'time' that parses the hours and minutes out
and a condition if (hour === 3 && minute === 55) .

After invoking from a button with the button script periodicUpdate_2(CF.activity()); the stuff is running OK every 60 seconds.

When the time is reached (3:55)
{CF.widget ("A4","B","C").scheduleActions();} is running OK

After that or after jumping to another activity/page the intervalTimer stops although the library is at system level.

I ever thought it would be running over the whole system on all pages and activities because the library is system level but it isn't so.

What's going wrong ?

Regards,
Fischi