ActiveX Callback Locks Front Panel

[bkling]

I have been having a problem with ActiveX event callbacks in LabVIEW 8.2.  If a callback occurs while the user is interacting with the frontpanel the frontpanel will lock.  The user will lose control of the front panel and will not be able to press any buttons.  This will last until the front panel loses focus (ie ALT-TAB).  I have been able to replicate this problem using a modified version of the ActiveX Callback Example using Internet Explorer.  I have attached this program, when it is running it will load a new website every 3 seconds.  There are two cases in this program that use different callback functions, one case works as expected, the other case will lock the frontpanel.

Any Ideas why this occurs, and how to fix it?

Also,
This seems similar to this posting, however I am using LV8.2 and this posting does not seem to have a resolution
http://forums.ni.com/ni/board/message?board.id=170&message.id=74227&query.id=57108#M74227

[Wiebe@CARYA]

This might be related too. It applies to 8.2.1, and there is no resolution.

http://forums.ni.com/ni/board/message?board.id=170&message.id=274346&query.id=2620#M274346

Regards,

Wiebe.

[bkling]

Interesting problem Wiebe, it seems that NI has some problems with the register for event callback.  I'm not sure if your problem is the same though, i tried yours out and it does crash my system, however my problem does not crash LabVIEW, it only locks the front panel.

Is this a LabVIEW bug? what do the NI people think?

[Donovan_B]

Hi bkling,

I'm not sure why you are using variants in the before navigate callback.vi.  It looks like the URL is a string.  I do not know why this is ocurring, but I will look into it further.  Does this work if the URL is a string instead of a variant cast to a string?  The variants look like the only difference between the two subVIs.  Is there a reason you can't use strings instead?

[bkling]

I have to use variants because the URL is a variant.  The problem will still occur if I use a variant as the user parameter.
Thanks,
Bryan

[Donovan_B]

Hi Bryan,

Let me look into this further and I will let you know what I find out.

[bkling]

Donovan, and ideas?

[Donovan_B]

Hi Bryan,

I don't know why the front panel is locking up, however, this has been reported to R&D (# 4H7H2QCL) for further investigation.  Thanks for your feedback and I'm sorry I don't have an solution for you right now.

[Hamm]

I believe that I am experiencing the same issue, has there been a reolution to this yet?

[bkling]

nope, not as far as I know. 

I basically ended up writing my own interface for the device i wanted to control since the activex was rendered useless by this LV bug.

It could be resolved in 8.6 as I haven't tried it in 8.6 but I doubt it