Hacker’s Guide to Visual FoxPro
An irreverent look at how Visual FoxPro really works. Tells you the inside scoop on every command, function, property, event and method of Visual FoxPro.
_DblClick, _IncSeek
These system variables control two aspects of the user interface. _DBLCLICK determines how long the user can pause between mouse clicks and still have it considered a double-click. _INCSEEK determines the speed for incremental search in list and combo boxes.
Usage
_DBLCLICK = nSeconds
_INCSEEK = nSeconds
nSeconds can range from .05 (1/20th of a second—we don’t know anybody who can double-click that fast) to 5.5 (handy for someone with a physical disability that makes double-clicking or typing quickly difficult). Because the ability to double-click varies widely from one person to the next, you’ll make your users really happy if you let them set _DBLCLICK through your application.
Of course, we and our users would be even happier if this setting were controlled by the similar setting in the Windows Control Panel. Happily, as of VFP 7, it is: _DBLCLICK gets its initial value from the setting chosen by the user in the Mouse applet.
Prior to VFP 7, _DBLCLICK had a second use: controlling the speed of typing for incremental search. We’re delighted that Microsoft decided to follow our advice and create a new system variable for this item. _INCSEEK (which also draws its initial value from the double-click setting in the Mouse applet!) determines how much time can pass between keystrokes and still take advantage of the incremental search feature of combos and lists.
Since users’ ability to type may be quite different from their clicking ability, you may want to uncouple _INCSEEK from _DBLCLICK and provide a facility for the user to adjust this value in your applications.
Example
_DBLCLICK = 1 && 1-second delay
_INCSEEK = ThisForm.spnIncSeek.Value