Install Virtualbox Guest Additions in OpenSUSE 12.2

Opensuse 12.2 by default has the virtualbox guest additions inbuilt. But if you want to reinstall then follow the steps.

First install the C compiler and make utilities required to compile the guest additions.

sudo zypper in gcc make

Now install the kernel development packages for the current distro version

Find the kernel type

~> uname -r
3.4.28-2.20-desktop

Update the kernel

~> sudo zypper update kernel-desktop

Now install the kernel development files

~> sudo zypper in kernel-devel

Now reboot suse. After the reboot click Devices > Install Guest Additions in virtualbox window.
Now go to the guest addition cd from a terminal. For example on my system the path is

cd /run/media/silver/VBOXADDITIONS_4.2.6_82870

Or open the pcmanfm file manager and click the CD icon on the left. Go inside the directory from a terminal and run the Linux installer as root.

silver@dhcppc0:/run/media/silver/VBOXADDITIONS_4.2.6_82870> sudo ./VBoxLinuxAdditions.run

If the whole installation process goes fine, then the terminal should show something like this

silver@dhcppc0:/run/media/silver/VBOXADDITIONS_4.2.6_82870> sudo ./VBoxLinuxAdditions.run 
root's password:
Verifying archive integrity... All good.
Uncompressing VirtualBox 4.2.6 Guest Additions for Linux..........
VirtualBox Guest Additions installer
Removing installed version 4.2.6 of VirtualBox Guest Additions...
Removing existing VirtualBox non-DKMS kernel modules                 done
Building the VirtualBox Guest Additions kernel modules
Building the main Guest Additions module                             done
Building the shared folder support module                            done
Building the OpenGL support module                                   done
Doing non-kernel setup of the Guest Additions                        done
Starting the VirtualBox Guest Additions                              done
Installing the Window System drivers
Installing X.Org Server 1.12 modules                                 done
Setting up the Window System to use the Guest Additions              done
You may need to restart the hal service and the Window System (or just restart
the guest system) to enable the Guest Additions.

Installing graphics libraries and desktop services components        done
silver@dhcppc0:/run/media/silver/VBOXADDITIONS_4.2.6_82870>

It should show done for all entries, mainly the "Building the main Guest Additions module". After the installation completes, reboot suse again.

After reboot suse should take proper screen resolution based on the dimensions of the virtualbox window. "Switch to Seamless Mode" option should be enabled in the View menu of virtualbox window.