Hi Jean Marc,
if you want to set the background for a layout use
layBar = app.CreateLayout( "Linear", "Vertical,VCenter,FillX" );
layBar.SetBackground( "/res/drawable/bar_gray" );
Basically you can set the background of any object, even buttons, but sometimes the results are not satisfying or it simply don't work.
Please note the path to the image or pattern. Above case use the AndroidScript internal files. If you want to use your own file,
please place it in the subfolder "Img" of your script. The filetype should be "png"
lay.SetBackground( app.GetPath() + "/Img/Tile.png", "repeat" );
Hope this helps.
best regards
Schnee