See here why it is a problem: http://jsfiddle.net/bSD3M/
The selected option, that is placed inside a ui-btn-text, gets corners cut off the first letter if it fills the entire width. I know it's minor, but I currently don't really understand why ui-btn-text needs border-radius anyway (then again, I haven't seen everything!).
(Note: I am testing this in Firefox; I don't see the issue in Chrome)
Button: removed border-radius inherit for ui-btn-text and added it to…
… listview because that's the only place where we need this. Fixes #5709.
Thanks for submitting the issue.
ui-btn-text needs to inherit the border-radius in listviews because thumb are nested in that element and those need to get the same radius at the applicable corner. Since this is the only case I removed the generic rule and added a specific rule in the listview CSS to fix the issue you reported.