Все, кто читал хелп.

Specifies the time interval that is open for keystrokes within an incremental seek such as within a Listbox or ComboBox control.


_INCSEEK = nTicks



Parameters
nTicks


Specifies the time interval in seconds. Internal timing is measured in clock "ticks," which are each about 1/18th of a second. If you store an integer or decimal value to _INCSEEK, Visual FoxPro may store it as a slightly different value due to rounding to ticks. _INCSEEK can range from 0.05 to 5.5 seconds (1 to 100 ticks).
Remarks
Applies To: IncrementalSearch Property

In earlier versions of Visual FoxPro, the value for _DBLCLICK also determined the incremental search interval. The default value for _INCSEEK is 0.50.