I can replicate the issue and forward the issue into our developer. 

For temporary workaround, if you want to define clientside events, please placed it outside WebPaneManager. 

After define all WebGrid clientside events, you can place it back inside WebPaneManager again.
The event is not fired because it is not defined automatically in html code.

e.g it should be defined in clientside events tag.

<ClientSideEvents OnAfterInitialize="WebGrid1_OnAfterInitialize" />

Regards,
Handy

Well, this is not the only issue here, any control you place inside the pane manger, after you put them inside the pane manger, and using the GUI designer, no changes will take a place, you actually will not get any change you make using the GUI. The only thing works is if you write everything manually without the GUI tools, or as you said, by taking it outside the Pane Manager which is kind of frustrating.

Thanks,

Maged

Hello Maged,

So, I can assume that all changes via designer properties are not also persisted in html code? 

Regards,
Handy

Yes, and this is really causing lots of issues and frastration to devlop.

Hello Maged,

Ok, Thank you for your report. I have marked the report to our developer teams and would ask them about the fix.

Regards,
Handy

Please let me know when there is a fix!

Hello Maged,

After discussed with our developer teams, it seems this is not bug from our side.
The issue can be only replicated in VS2008. It is a issue/bug in the old version.
FYI, the same code is also used in VS2010 and everything works fine.
I suggest you to migrate into VS2010.  
It won't be quite trouble if the user migrated to vs 2010. You can still target older .net framework in VS2010. Hope this helps.

Regards,
Handy

Ok, so you mean its a vs 2008 issue, okay I believe you!