Choice window with parameters
alertes=new Array("LightGrey","black","yellow","red",14,"Arial",150,100,200,100);
chaines=new Array("Fill rectangle","red","blue","black","Confirm");
Parameters for look:
Colors background, border, button, text, size and font for text, coordinates
left top vertice, width and height of window.
Text to write:
Array of phrases à afficher, first as invite, then choices and last for button.