## Input/Output Device Driver Reference

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### Click Locking

Click locking is the process by which the touch (X,Y) coordinate locks onto a value before being sent to the system as emulated mouse data.

Note: Click locking affects touch data only when it is sent as emulated mouse data and does not interfere with the normal use of an IBM PS/2 Mouse, if one is attached to the IBM Touch Display, or the data is sent in full touch pointing mode.

Click locking is performed because some actions with a clicked mouse button require that little movement of the mouse pointer itself take place. Click locking makes double clicking using the Touch display easier, because there is no need to maintain the touch position at exactly the same point between clicks.

The following examples of this can be found in the OS/2 Presentation Manager:

Clicking on an icon to bring up the system menu

Double clicking to activate the window

Clicking on an icon, when attempted with the Touch display's emulating the mouse, occasionally can result in the icon's moving a few pels, because the PM Desktop misinterprets the click down with associated movement as a drag operation to move the icon. PM decides that if the movement is more than a few pels, it must be a click with drag rather than a simple click. Thus, even a single click action sometimes can be unsuccessful.

The double-click action is more difficult: even if the first click can be made without moving the icon, the second click must be done at the same position. PM permits a small movement of 6 pels in the X direction and 8 pels in the Y direction. With a great deal of practice, this condition can be satisfied, but perhaps with only a 20% success rate.

    /------------------------------------------------------------\

    |Tip: For the least X,Y movement, keep the force variation to|

    |a minimum. In other words, do not press harder than         |

    |necessary to achieve the button-down threshold; and do not  |

    |lift off completely between clicks; rather, just release    |

    |sufficiently to go below the button-up threshold. The usual |

    |outcome will be that the icon will move and/or the system   |

    |menu will appear.                                           |

    \------------------------------------------------------------/

Click locking attempts to minimize the difficulty of maintaining the X,Y position while button clicking. While mainly applicable to PM, the click- locking technique is useful also in the DOS 4.0 shell and any application ( usually in graphics mode) that uses a mouse.

The following click-lock options can be chosen:

No click locking
Single click locking
Double click locking