refactor to be tiling window manager friendly

sources/scripts/dotgrid.js

@@ -51,7 +51,7 @@ function Dotgrid(width,height,grid_x,grid_y,block_x,block_y,thickness = 3,lineca
 
   this.install = function()
   {
-    document.body.appendChild(this.wrapper);
+    document.getElementById("app").appendChild(this.wrapper);
     this.wrapper.appendChild(this.element);
     this.element.appendChild(this.guide.el);
     this.element.appendChild(this.guide.widgets);