Set DoubleClickInterval very low!

Richard Gaskin ambassador at
Thu Aug 4 10:48:49 EDT 2016

Peter M. Brigham wrote:
 > So I must not be understanding this. If you want something to happen
 > on mouseup and something else to happen on mousedoubleup, then how
 > do you do it?

The other question is *why* would you do it?

A control usually has an interaction semantics role of either a verb or 
a noun.  A push button, for example, is a verb, performing an action, 
while a Finder icon is a noun, where it must be selected first and then 
use some other control as the verb (usually a menu item) to apply an 
action to it.  Sometimes a noun object may also support a shortcut for 
the verb object, such as a second click on the noun object, but the 
essential role of the noun object remains fairly consistent throughout 
the interactions, in which the first click merely selects the object and 
performs no action.

When determining whether a circumstance is an edge case or a common one, 
I like the rule of three:  Can you think of three examples in apps from 
established vendors like Apple where a control acts as both a verb and a 
noun, i.e. provides a direct action on a single-click and then a 
different action on a double-click?

In the rare case where this may be useful in a context that doesn't 
confuse or frustrate the user (accidental double-clicks are not 
uncommon), the OS routines that differentiate single- and double-clicks 
would require a pause equal to the OS' doubleClickInterval, as
Mark noted:

    In order for you to be able to do completely different things
    on click and double click you need to wait and see if a double
    click occurs before the doubleClickInterval and if it does not
    *then* do the single click action. After all, the engine is
    not clairvoyant.

    This is why click then double click should always be an incremental
    and related action - unless you want a pause in processing the
    single click.

This has come up a few times on this list over the years, and while I 
generally try to avoid mixing verb/noun semantics and don't have one 
handy, I would imagine a search at Nabble may help, or perhaps Michael 
Doub has already included such an example in his Master Library stack.

  Richard Gaskin
  Fourth World Systems
  Software Design and Development for the Desktop, Mobile, and the Web
  Ambassador at      

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