Comment 3 for bug 708269

Just a note: you don't need XML editor to change a pattern while it's in use to fill other objects.
Create your object (e.g. like your rounded corner square). Make a "linked" copy of it (using Alt+D) and convert the linked copy to pattern. Now if you make any changes to the original object, all the objects using the pattern will update as well.
The bug reported here still applies, as in, you still need to force a canvas update by zooming in/out.