After uploading the .xap file to the webpart doc lib, and after pointing the xap file with an object tag in the content editor part's source code, you will not see the control.
As the tag never understands the X, Y directinal values, it will display over the content editor.
Content Editor webpart was developed to be enclosed to the page's hidden DIV property, thus causing the tag control to fall in the invisible Div.
- Set a fixed height and width in the web part appearance properties, and give the object tag a height and width of 100%,
- Set an absolute height and width for the object tag and leave the web part with non-fixed height and width