Flush Event Queue doesn't work with "Key up"

Question

Hi,
probably just a simple thing I am missing here. See the attached VI (including SubVI). In case 1 I fetch the Key Up event for ENTER and issue a Value Change on the Stop Button. This results in a check for the string length and in case it is too short brings up a dialog telling you the ID string is too short and brings you back to the ID entry. Unfortunately - when confirming the dialog with ENTER instead of using the mouse on the button theKey Up event fired again and therefore fetched by the Event Structure.
So I thought I just flush all events in the queue. To be sure, I put a time value on the flush function which proceeds AFTER the dialog is completed, so the ENTER Key Up should be deleted as well. Bummer is - it doesn't work. Anyone know why?
I tried as well with the dynamic event, which I unregistered right after the Stop Event is issued in the Key Up case. I then "re"register for the Key Up event at the same time/position as the flush event queue function is positioned now in the VI below. Still no joy.
What is my mistake? Thanks a lot.
Solved!
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Attachments:
Manual_ID_Entry.llb ‏47 KB

Answer 1

comrade wrote:
I don't understand 2 things:
a) Why is the Key up event even fired? It doesn't come from the VI where the event structure resides and to which "Instance" the event is bound (VI->Key up), but from the dialog box (which is a different VI). Unless a calling VI inherits all events from its SubVIs or something like that.
b) Why isn't the event fired by the button in the dialog box discarded as the flush event queue function is supposed to perform?
Because you are slow.  Not you personally.  But compared to the computer, you just don't stand a chance.  So you hit the Enter button on the dialog.  That dialog's OK button activates on the key down.  So the dialog is long gone by the time you manage to get your finger off of the Enter key.  In fact, you loop should be back around to be waiting for an event first.  So it is waiting for an event when you finally get your finger off of the button.  Hey, we have a Key Up event!
Your current checking for the validity of the id is just flat out annoying.  Use the Key Down? event to check for a valid character being entered.  Notice the '?' in my choice of event there?  That means it is a filter event.  This means you can throw away (discard) the character being pressed before the control even sees it.  You could also discard if there are already enough characters (Greater Or Equal, not Equal).
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