Disabled Events Still Firing (for DropDownOpened)

[sculver]

I am developing a solution where I will need to go and pull information dynamically from a web service.

When the call is complete, I wish to open the drop down so the user will see all the results. However, I also need to run code in the DropDownOpened event as well, and do NOT need it to fire during this time. (I.e., when the user tells it to open, I need to run some code, but when the code auto opens it, I need something else).

I thought this would be no problem, as I should be able to unsubscribe from the event using the standard -= ????? However, to my surprise, even though I did this, the event still fires.  So for example, if I did this:

radMyCombo.DropDownOpened -= new EventHandler(MyEventHandler);
radMyCombo.IsDropDownOpen = true;
radMyCombo.DropDownOpened += new EventHandler(MyEventHandler);

I expected this to work, but it did not.  What am I missing????

[Valeri Hristov]

Hello Stephen,

The problem is because the DropDownOpened event is asynchronous, e.g. it is raised in a Dispatcher.BeginInvoce callback. I will check whether this is needed anymore, I remember fixing a problem in an older version this way (I know, it is a bad thing to use Dispatcher), which might be irrelevant now. To workaround the problem I would recommend using a flag:
- when you populate the combo you rise the flag, then open the dropdown
- when the dropdown opens, if the flag is raised, do nothing, but lower the flag, otherwise execute the code you need.

Kind regards,
Valeri Hristov
the Telerik team

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[sculver]

Thanks, I did the workaround and got it to work.