LabView 8.2 hangs when trying to edit multicolumn listbox cell on tab control

[fgowash]

The message subject states the problem. The only other thing that might be useful is that the code processing the listbox is within an event structure. A scaler control and boolean operate OK independently until the list box cell is selected and the keyboard enters one digit causing the hang.

Thanks, Fran

[Chris_Cilino]

Fran,

From the sounds of your email, the hang is occurring at run time. Is that correct? In other words your program is actually running when the hang occurs, correct? If that's the case, then do you have multiple event structures? If not, I tried putting a listbox in a tab control and editing the listbox and LabVIEW didn't hang.

Would you be willing to post a SMALL piece of your code that seems to demonstrate the problem?

Chris C

[fgowash]

Chris,

There are two event structures in the application each with several cases. The case  in question does not have multiple event structures.

I have determined that the tab control is not an issue here. What happens is that when I click on the listbox control the cell is outlined. Then when I type an entry the app hangs. I have also been able to get this to work as a simple stand alone vi. Unfortunately no luck here.Being able to edit this controls contents is vital to this application and is driving me nuts....so I have reworked the approach and now no longer have the hang problem. It would be useful, however, if someone had an example of a listbox triggering an event with cell editing where the individual cell changed contents are checked for run time constraints like invalid data.

Thanks,

Fran

[Dennis_Knutson]

There can be all sorts of problems with multiple event structures in a single VI and is not recomended. Have you read the caveats and recomendations for using events? This is in the on-line help and one of the problems described is the user interface hanging up. Why do you need multiple event structures?

[Ben]

Dennis wrote "multiple event structures in a single VI and is not recomended. "

BINGO!

And I will wager five stars that "Lock front panel until the event case for this event completes" is involved as well.

Ben

[Dennis_Knutson]

Wouldn't it be nice if a future version of LabVIEW actually prevented this sort of thing from happening. Like if you drag the event structure to a VI, the event stucture then becomes greyed out and disabled on the palette?

[fgowash]

Well I have to admit that there were two event structures in the vi. No good reason. I have since eliminated one of them.

I would like to point out that the front panel was not locked out so so much for the 5 stars.

Also can't seem to find the reference to "multiple structures" in a vi and I did read the crevats and recommendations!

I mentioned that I changed the approach so cannot produce the same code. Things are simpler now.

Thanks,

Fran

[Ben]

Thank you for the update Fran.

I lost my bet and you earned your stars.

So it sounds like the issue was the multiple event structures alone.

I just like to keep track of what the final fixes are.

Ben

Message Edited by Ben on 12-06-2006 04:50 PM