I haven't had the opportunity to run the same tests you are running. But I'd recommend you to first open a backup of all QVWs with the Desktop of the new version, and save them with the new version. Then make the tests with these files.
In regards to the selection box, there have been some issues fixed in the 11.20 SR3, but mainly happening in the Ajax client, if any. Check anyway the release notes of this version here so you can check if there might be known issues affecting to your developments.
Hope that helps.