Many of us have a lot of text chat traffic to deal with. Previously, we were able to set the transparency of our chat windows.
This allows us to keep an eye on chat without completely obscuring the world. When managing high-traffic community areas, this is very very important.
"Chat bubbles" are allowed to be adjusted in transparency in Viewer 2.0. In Viewer 2.0, we should be able to adjust the transparency of the chat "toasts" and the Nearby Chat/plaintext chat window as well, like in viewer 1.2 (and similar to the Chat Bubble opacity.)
Please allow this to happen. This is my major hinderance in using Viewer 2.0 right now. Chat and chat History simply obscures too much of the screen and should be allowed to have an adjustable opacity. It can be 'ganged' to Bubble Chat opacity if desired.
EDIT AND UPDATE: Many in comments have expressed that this ability for inactive/backgrounded windows to be transparent, or to be able to set opacity of windows should not only be limited to the Chat Toasts/Nearby Chat/Plaintext Chat windows, but all possibly obscuring windows such as Script Editor, Object Properties, – and essentially all floaters when they do not have focus/are backgrounded.
The lack of transparency in these windows (something that was available on previous versions quite comprehensively for most windows that would get in the way) cause this UI to be far more invasive than past iterations.
Note that many modern UIs, such as Windows 7, OS X, Trillian Astra, etc - use transparency to cause less obscuration and impact to the user.
In a virtual world this is even more important than on the desktop however, as awareness of the world behind the UI is not only important, but is likely the main focus of the user's interaction.
Window transparency/adjustable opacity is a sorely needed aide to usability and accessibility of the SL world. It is not liklely to cause any further confusion to new residents as it is a paradigm that most operating systems already use. It does however keep the UI from being as much of an obstacle or barrier between the user and the world. And that seems to have been left behind in the 2.0 redesign.