Network Management doesn't understand/support VLAN interfaces/connections.

Reproducible: Always

Steps to Reproduce:
1. configure your system such that there are only VLAN connections (I configured mine by manually creating RedHat-style ifcfg files - an example of one such is attached)

2. verify that NetworkManager is able to connect the VLAN(s), this is what nmcli reports on my system:
# nmcli nm
RUNNING         STATE           WIFI-HARDWARE   WIFI       WWAN-HARDWARE   WWAN      
running         connected       enabled         enabled    enabled         disabled  

# nmcli con
NAME                      UUID                                   TYPE              TIMESTAMP-REAL                    
System em1 vlan 20        0caec10a-57b2-c417-090a-d8f16da77e2d   vlan              Thu 04 Oct 2012 11:06:08 PM CEST  
System em1 vlan 10        9875791f-d51b-e1f9-6766-853b8168c97a   vlan              Thu 04 Oct 2012 11:06:08 PM CEST  

# nmcli dev
DEVICE     TYPE              STATE        
p4p1       802-3-ethernet    unavailable  
p3p1       802-3-ethernet    unavailable  
vlan10     vlan              connected    
vlan20     vlan              connected    
em1        802-3-ethernet    disconnected 

3. start a KDE session and observe the state of the Network Management widget/systray icon and the information it displays
Actual Results:  
The Network Management systray icon has the "not connected" appearance. The information in the popup window displayed when the systray icon is clicked doesn't match that provided by nmcli.
See the attached screencap of what is displayed on my system and compare with the information nmcli reports which I mentioned in the step 2)

Expected Results:  
The systray icon has the "connected" appearance. The information in the popup window matches that provided by nmcli, namely:
- the VLAN interfaces are included in the list of the interfaces in the left hand half of the popup window
- the VLAN connections in the right hand half of the window are only highlighted when hovering over the appropriate VLAN interface (and not when hovering over the underlying 802-3-ethernet interface)

A side effect of the described behaviour is that it is not possible to connect through the GUI to any VPN as the widget just does not display any such option.
The connection management dialog window most probably needs an update too as it currently treats the VLAN connections as plain (Wired) Ethernet connections (I was too afraid of possible ill effects to try to edit the VLAN connection properties using that tool)