* What is an On-Screen Keyboard?

An on screen keyboards allow an individual to completely control the computer using only a mouse. There are several on screen keyboards available for Linux.

Ubuntu Linux comes with an on screen keyboard called onboard, which can be used to not only control the system, but also login.

In addition to offering standard onscreen keyboard functions, onboard also allows you to save pre-formatted messages and print them quickly and easily. Using this, you could store a command you frequently use, a web address, or perhaps a message to a friend.
Getting Started

If you are using Ubuntu 7.10 or greater, onboard should be installed by default, but you can also download it in the Synaptic Package Manager.

You can start onboard by opening up a terminal and typing:

onboard

If onboard is not installed, you can install it, as mentioned above, using the Synaptic Package Manger or from the terminal. To install it from the terminal, type:

sudo apt-get install onboard

* Changing Onboard’s Default Size and Position

By default onboard is positioned on the top left corner of the screen, but this, as well as the size, can be changed. To control the size you can use the -s parameter.

Open the terminal and type:

onboard -s 640×205 -x 0 -y 0

The -s parameter is telling onboard it should be 640 pixels wide and 205 pixels high.

Some people like to have onboard span the entire width of their screen, so you could use your monitors resolution to figure out a good width for onboard.

For example, if your monitor’s resolution is 1200 x 1024, you could use the following command to have onboard span the entire width of the monitor:

onboard -s 1200×205 -x 0 -y 0

Once you find a size that works for you, you will need to adjust onboard’s screen position.

The -x and -y paramaters control the onboard’s screen location. These are like the x and y coordinates on a graph, with (0,0) corresponding to the upper left corner.

Again, you can use your current resolution to figure out the x and y coordinates.

For example, subtract the height of onboard, 205, from the height of the monitor, 1024.

This gives you 819, positioning onboard at the bottom of your screen.

onboard -s 1200×205 -x 0 -y 819

Go ahead and do some playing around, but once you find something you like, make sure you save the command, because you will need it for the next few steps.

* Setting Onboard to Start at After Login

Once you have found a size and position that you like, you can set onboard to start when you logon. Make sure you leave the terminal open or copy the command from above into a text editor, because you will need it in the next step.

One way to set onboard to start when you login is in the Assistive Technologies menu.

Goto:

System → Preferences → Assistive Technologies

Click on, “Preferred Applications” and select the “Accessibility Tab.”

Change the bottom drop down under the word “Mobility” to “custom.”

Now, go ahead and paste in your custom onboard command into the white box labeled “Command.”

Check the box next to “Run at Start.”

Onboard will now start when you login.

* Using Onboard to Login

The above method will set onboard to start as soon as you login, but if you need to be able to use an on screen keyboard to login and enter your username and password, you will need to make a few more changes.

You will be editing your “/etc/gdm/Init/Default” file, but as is always the case, you will want to make a copy of the file before making any changes.

In a terminal type:

cd /etc/gdm/Init/

sudo cp Default Default.bac

sudo gedit Default

At the bottom of the file, right before “Exit 0,” add the following:

fi

exec onboard -s 1200×205 -x 0 -y 819 &

You will probably want to use your custom onboard command that you created above, instead of “onboard -s 1200×205 -x 0 -y 819.” Remember to include the ‘&’ after the onboard command.

You will also need to select the plain login theme.

Goto:

System → Administration → Login Window

After entering your password, select the local tab. Change the style to “Plain.”

You should now be able to use onboard to login. To test it, first make sure you save and exit any programs you are running and press “ctrl + alt + backspace.”

The on screen keyboard should show now load when your computer turns on.

You might have to change the x and y coordinates a little bit, but remember you can also use the mouse to move onboard around once it is loaded.

Sumber : Anonymous