var menu_cm:ContextMenu = new ContextMenu();
menu_cm.customItems.push(new ContextMenuItem("Save...", doSave));
function doSave(menu:Object, obj:Object):Void {
trace(" You selected the 'Save...' menu item ");
myBtn_btn.menu = menu_cm;

with a right click on the button named: "myBtn_btn" the menu will appear with the item "Save"

Question: I need to customize this code that whenever the user right-clicks on stage with _ymouse>300, for eaxmple,
this "Save" item appears.