change cursor style

Hello, I want to change the style of the cursor when (for example) filtering the grid, I try the code below, but cursor don´t change.
It is necessary to make it otherwise when you use AW buttons.
I have tried this with a simple web page with two buttons (if you touch first button, the cursor takes the style "wait" and if you touch the other button, cursor takes the default style).
Why this not work in my application web.

btnFiltrar.onControlClicked = function()
{
document.body.style.cursor = "wait";
if (TabActivo == 0){
for (i=0; i<tablaClientesAsync.getCount(); i++){filasClientes[i] = i;}
filtradataview(DGridClientes);
}
if (TabActivo == 1){
for (i=0; i<tablaProyectosAsync.getCount(); i++){filasProyectos[i]= i;}
filtradataview(DGridProyectos);
}
if (TabActivo == 2){
for (i=0; i<tablaDatosAsync.getCount(); i++) {filasDatos[i] = i;}
filtradataview(DGridDatos);
}
document.body.style.cursor = "default";
}