function Gstart(g,t){

 if(tsG==-1){
 if (t == 0) { //AE
 ts[g].startTime=Browser.getTime();tsG=g;currG=-1;
 } else {
 ts[g].startTime=t;tsG=g;currG=-1;
 }
 }
 else{ts[tsG].stopTime=t;tsG=-1;currG=g;}
 }