A friend has a strong hand tremor, much like those evident with Parkinson’s disease. When using the computer she finds it almost impossible to hold her hand still long enough for a double mouse click, and instead the cursor nearly always moves between clicks which moves the icon but does not activate an application. Changing the double-click speed has not resolved the problem. Is there any way to reassign a keyboard key to act as the left mouse button? Using this method she could move the cursor and, if the cursor is still over the icon, release the mouse followed by hitting the reassigned key twice to simulate a double-click. This can be done quite effectively using a laptop touchpad and external mouse - move the external mouse, release the mouse, and then double-click the left button on the laptop touchpad. However, is there a way to do this with a desktop computer? The computer is running Windows XP.

You will be glad to know that there is a way to control the mouse and mouse-clicks using the keyboard in Windows XP with an accessibility feature called MouseKeys. The MouseKeys utility allows you to move the mouse cursor on the screen using the keyboard but, more importantly for your situation, assigns specific keys on the keyboard to single-click and double-click functionality. Since you still wish to use the external mouse to position the cursor, and just the keyboard to execute the clicking functionality, MouseKeys does not lock-out the external mouse. As such, you can use the external mouse with MouseKeys running and just use the keys to simulate a click when needed (although you may wish to use the keys to move the mouse as well, if you need precise mouse control).

To start MouseKeys go to the “Start” menu > “Control Panel”. In the Control Panel window that appears, open the “Accessibility Options” control panel (if you are prompted to “Pick a task…” click the “Accessibility Options” link at the bottom of the window). The Accessibility Options control panel should now be open. Click the “Mouse” tab and tick “Use MouseKeys”. Once MouseKeys has been enabled use the numeric keypad on the keyboard to control the mouse. However, make sure NumLock is On otherwise the MouseKeys will not work. To enable and disable NumLock there should be a key in the top-left of the numeric keypad which triggers this function, together with an indicator light on the keyboard indicating when NumLock is enabled or disabled.

The following keys on the numeric keypad are mapped to the various mouse functions:

• 7 - Up and Left
• 8 - Up
• 9 - Up and Right
• 4 - Left
• 6 - Right
• 1 - Down and Left
• 2 - Down
• 3 - Down and Right

While these may seem difficult to remember, when you look at the numeric keypad you will see that they correspond with the physical location of the keys on the keypad and that there are direction arrows on the keys.

The following keys correspond to the clicking functionality on the mouse:

• 5 - Mouse Click
• + - Double Click

As such, to obtain the behaviour you described in your question, you can use the external mouse to position the cursor and then either the 5 key or the + key to trigger the mouse clicks. Make sure you are using the + key on the numeric keypad and not the + key in the row of numbers at the top of the keyboard, you can only use the numeric keypad keys to simulate the mouse.

There are some other keys which you can use for dragging functionality:

• Ins (or 0) - Begin drag
• Del - End drag

If you wish to customise MouseKeys further, go back into the Accessibility Options control panel and Mouse tab then click the “Settings” button beside MouseKeys. From within you can change various settings including the cursor speed, when controlled by the keypad, and also the ability to speed up the mouse cursor on demand. You can also modify the behaviour of MouseKeys to be running when NumLock is On or Off, overriding the default behaviour.