Try this one:

script: /* Save to PNG */
var vp = moi.ui.getLastClickedViewport();
if (!vp) { vp = moi.ui.mainWindow.viewpanel.getViewport('3D'); }
var filename = moi.filesystem.GetSaveFileName( 'Save', ' (*.png)|*.png' );
var st = [], settings  = ["view.viewportBackgroundColor", "view.lineWidth", "grid.display", "grid.showXYAxes", "view.showAxisIcon", "view.meshAngle"];
for (var sv in settings) { st.push(moi[settings[sv].split('.')[0]][settings[sv].split('.')[1]] ); } 
moi.view.viewportBackgroundColor = 0xFFFFFF; 
moi.view.lineWidth = 3; 
moi.grid.display = false; 
moi.grid.showXYAxes = false; 
moi.view.showAxisIcon = false; 
moi.view.meshAngle = 3; 
vp.render( 4000, 2500 ).save(filename);
for (var sv in settings) { moi[settings[sv].split('.')[0]][settings[sv].split('.')[1]] = st.shift(); }