I added a branch on github that has all the code needed to show the issue between 2.0 and 2.1.

See: https://github.com/vrsource/sencha-SlideNavigation/tree/dev/bug_21

f you load the index_nocmd_20.html and index_cmd_21.html you will see how the code works in 2.0 and 2.1.

It appears to me that there is an issue with the new way that docking and layouts are being handled in 2.1 and that it is conflicting with some of the assumptions made for positioning the slidenavigation list and container.