This code is working in Extjs 4.0.2a but when converted to 4.1 it no longer works and gives an error
Uncaught TypeError: Cannot call method \'query\' of undef
I was able to get it working in 4.1: you have to add quotes around the id of the renderTo element, like:
renderTo : 'divtag',
Without quotes it was looking for an undefined variable named divtag.
Once I ran that I got no errors, and then I just did panel.show() to render it.
panel.show()