* Removes the chat button in the CallPanel during a conference call.
  * Other recent changes in earlier versions:
  * build.3907
  * - Fixes NPE in contact right button menu and chat window. Fixes a problem with yahoo deny authorization requests.
  * - Makes possible making video call without audio, and sharing the desktop from machine without audio device. Updates zrtp to use the first available stream as master, if more than one stream use the audio one. 
  * build.3906
  * - Removes button rectangular border under Linux. Based on Daniel Zucchetto patch proposed on dev mailing-list with subject: UI improvements on labels and buttons.
  * build.3905
  * - Adds property which can make provisioning mandatory, and if user cancels application will exit.
  * - Fixes scroll going to top problem in chat window.
  * build.3904
  * - Commits work in progress on fixing issues with video conferences. Fixes an ArrayIndexOutOfBoundsException in audio level UI.
  * - Fixes a NullPointerException in CallPeerMediaHandler#close().
  * build.3903
  * - Adds some logs in order to track the disappearing main window bug.
  * build.3902
  * - Deletes a reference to MediaDeviceSession in MediaDevice. Adds a getCallPeer() method to RemoteControlListener and RemoteControlEvent so that we can determine which CallPeer has generated the event.
  * build.3901
  * - Shows newly created groups when using 'Hide offline contacts' filter.
  * build.3900
  * - Commits work in progress on fixing leaks of CallDialog.
  * build.3899
  * - Fixes subsequent open of chat history urls when trying to focus back on the chat conversation by clicking the mouse on the chat history panel.
  * build.3898
  * - Fixes problem with deleting chars on macosx java 1.5 and handling some special chars in the written text. Fixes subsequent open of chat history urls when trying to focus back on the chat conversation by clicking the mouse on the chat history panel.
  * build.3897
  * - Stops sending typing notifications if contact is offline.
  * build.3896
  * - Tries to address issues with the support of video conferences such as the CallDialog not resizing properly at the conference focus, a crash in FFmpeg/sws_scale.
  * build.3895
  * - Fixes a problem where adding contacts to newly created group is impossible. Fixes a problem with moving contacts to group and double contact entry shown. Renames protocol groups when meta group is renamed and fixed its storing.
  * - Changes tests as metacontactlist behaviour has changed, now proto-groups also get renamed.
  * - Tries to fix scroll going to top problem in chat window.
  * - Disables send file button when in a group chat. 
  * - Commits work in progress on fixing leaks of every CallDialog and ChatWindow.
  * - Improves DTMF configuration (auto, RTP, SIP INFO or INBAND). Creates a common interface for starting and stopping (RTP or INBAND) DTMF tones into AudioMediaStream interface and its implementation. Reverting DtmfTransformEngine to use previous threaded DTMFDispatcher.
  * build.3894
  * - Corrects gray background checkbox problem on Linux for the account list in the Tools->Options->Accounts menu.
  * build.3893
  * - Fixes (on Java 1.6+ and not 1.5) a leak of pretty much all Window instances created by the application. ChatWindow and CallDialog are still leaked though because they have other, remaining retain paths.
  * build.3892
  * - Fixes a problem where a group can be shown twice in the contactlist.
  * - Corrects gray background for checkboxes on linux. Based on Daniel Zucchetto patch proposed on dev mailing-list with subject: UI improvements on labels and buttons.
  * build.3891
  * - Adds option to disable font support.
  * build.3890
  * - Hides answer with video button in incoming call dialog if remote side initiated video call but we are unable to send(missing/disabled video device).
  * build.3889
  * - Fixes "Log chat history" check box in the general configuration form. Reported by Davide Corda on the mailing list (subject: [jitsi-dev] General config: showHistoryCheckBox).
  * build.3888
  * - Ongoing work on cross protocol conference calls. Adds missing portaudio hotplug patch.
  * - Adds property to disable auto answer menu.