Hi again,

Thanks for the example file. However, the WebTab has AutoPostBackFlags set to on, as opposed to Async. Setting it to Async stops it from working. I suspect this is because the updatepanel requires a proper post back to be triggered?

This is why we used JS in our scenario, to trigger an Async postback on the client event SelectedIndexChanged, but this is the point where we run into errors. Looking online suggests we might have incorrexy AJAX assemblies, but all looks in place from what I can see

Hello Alex,

Currently there Is no way to achieve the mention events order, The reason is that the client side is the one that requests some job to be done on the server. This is the reason why client side events are fired before the server side events.

However, I modified the sample project in order to achieve only async postbacks . What I am doing is to call __doPostBack for the WebDropDown using __doPostBacks function`s parameters. With setting WebDropown as __EVENTTARGET I am causing async postback for the WebdropDown respectively for the updatePanel. Some further reference about __doPostBack function and its parameters could be found at:

http://aspalliance.com/articleViewer.aspx?aId=895&pId=-1

Now in my scenario async postback is triggered when ActiveTabChange event is fired and WebDropDown`s selected index is changed. For example:

Client side:
 <script type="text/javascript" id="igClientScript1">
 function causePostBack() {
 __doPostBack('WebDropDown1', ' ');
}

 function WebTab1_ActiveTabChange(sender, eventArgs) {
causePostBack();

}
 </script>
Server side:
 protected void WebTab1_SelectedIndexChanged(object sender, TabSelectedIndexChangedEventArgs e)
{

 int index = e.NewIndex;
 this.WebDropDown1.SelectedItemIndex = index; 
}

I hope you find this information helpful.

Please let me know if you need any further assistance with this matter.

Again, I can't thank you enough!

I think I've drilled down to the root of the issue. Having a WebDataGrid in one of the ContentTabs seems to be causing the issue.

Even just putting an empty WebDataGrid into a ContentTabItem, then clicking that tab, causes the following error:

Line: 4620
Error: Sys.ArgumentUndefinedException: Value cannot be undefined.
Parameter name: type

Again, this WebDataGrid is completely empty, and has been dragged and dropped from the toolbox and nothing else.

Without the WebDataGrid, everything works fine. Is this an issue with the WebDataGrid, or is there some underlying problem in our code? Again, the given WebTab options work fine without the WebDataGrid, so I'm assuming it's something wrong with how the WebDataGrid is set up.

Thanks again for all your help!

Ended up having a fiddle around and got it to work how I wanted (looks like it was a combination of incorrect properties and controls, but what they were I'm not too sure!). The posts here regarding updating a webdropdown from a webtab helped immensely however!

I am glad that you've managed to resolve this issue.

Thank you for using our controls.