Changes the dpi value (dots per inch) that affects the content of any control created afterwards.
Example - Demonstration
function OnStart() {
var dens = app.GetScreenDensity();
lay = app.CreateLayout( "linear", "VCenter,FillXY" );
app.SetDensity(dens / 2);
btn = app.CreateButton( "Press Me", -1, .1 );
lay.AddChild( btn );
app.SetDensity(dens);
btn = app.CreateButton( "Press Me", -1, .1 );
lay.AddChild( btn );
app.SetDensity(dens * 2);
btn = app.CreateButton( "Press Me", -1, .1 );
lay.AddChild( btn );
app.AddLayout( lay );
}