Are you trying to draw some window on that page you prinscreened? Be careful MyWindow have by default (don't know why) set attribute hidden = true (checked) --- when you uncheck this it will work. Hope it helps
You are trying to call something you have declared, but didn't set all parameters. Look for drop down menus and their storage or any grids and their storage etc. Blank screen appear almost always when is there an error like that. Btw worked it before? If not try to link your ext-all.css properly. Another reason why isn't window visible is you may have set your window "hidden" parameter to "checked" - its default - just try to set this to "unchecked" . Hope it helps
Though I can see each work in Architect canvas, I can't see them work in safari or chrome after I save them into my web server directory or user web server directory(I made some test apps in Architect, and they worked fine both in Architect canvas and safari/chrome).