When enabling 4 displays on a RHEL6 guest, display resizing doesn't work properly. There are a variety of issues.  And behavior is not always predictable.  
- Sometimes the 4th display is displayed as a vertical strip that is approx 400px wide;
- sometimes the 4th display jumps back to its previous configuration after attempting to resize it;
- sometimes the guest display doesn't get resized at all and virt-viewer simply scales it up to fit the window
- sometimes a display will turn black with a 'waiting for display...' message
- Sometimes guest displays pop open again immediately after disabling them via the virt-viewer 'view > displays' menu.

I'm not entirely sure which component the problem is in, or even whether if it's confined to a single component.

Some of the symptoms I've observed include:
- the server not responding to vdagent monitor config requests when 4 displays are enabled
- the server sending back a display channel MONITORS_CONFIG message with the old configuration, imediately followed by the new configuration (which causes the client to resize itself back to the old configuration).
- the server sending several display channel MONITORS_CONFIG messages in response to a single vdagent config request

When I check the xrandr configuration in the guest, it doesn't always seem to match what the spice client thinks the displays are set to.

In addition, even disabling displays and closing and re-opening virt-viewer doesn't appears to return the guest to a working state. A guest restart appears necessary to return things to a working state.

It's possible that this bug is related to bug #1008312


Test configuration:

Client: (fedora 19)
virt-viewer v0.5.7-61-gdd19f50
spice-gtk v0.21-34-ga1ae578

Host: (fedora 19)
qemu-1.4.2-13.fc19.x86_64
spice-server-0.12.4-3.fc19.x86_64

Guest: (RHEL 6.4)
spice-vdagent-0.12.0-4.el6.x86_64
xorg-x11-drv-qxl-0.1.0-4.el6.x86_64