Using the Command-W shortcut to close the Vienna window does not work in build 2200 after browser tabs have been opened. This bug is new to this build and did not exist in 2.1.2. To replicate the problem:
1. Press Command-T to open a new browser tab
2. Press Command-W to close the new browser tab
3. Press Command-W again, which should close the Vienna window but does nothing
Note that Command-Tabbing to another application and then back to Vienna reactivates the Command-W shortcut.