Setting focus on WPF ComboBox not always working

Question

I have a solution, that has two projects, the main one and a small shared control that's used as well. In our application, a certain feature opens this shared control in a new window. I want to set the focus to the first combobox in this control when the window opens.

In my code, on the window that loads the shared control, at the end of the _Loaded event, I set focus to this combobox. But when running the code - I still have to hit tab to have 'keyboard' focus on the box (as in, I would have to hit tab to then start typing the name of one of the items in the list).

If I set a breakpoint here, hit it, and then continue - it actually is set the way it should be. If I use a WPF inspector - IsFocused is also set.

Other things noticed:

If I hit tab (to get what I want), then tab back, it takes me to the last control on the form, not to this unknown control. This makes me believe the focus is set right, but for some reason doesn't have correct keyboard focus.
If I try to use MoveNext in code, it actually selects the next item in the window, outside of the control.

How do I properly set focus here? On another combobox in the 'main' project, just calling .Focus() worked correctly.

GameAlchemist GameAlchemist · Accepted Answer · 2012-07-11T11:23:28

try to postpone the focus() after all events are handled and bindings updated with QueueUserWorkItem. Something like this :

   public  delegate void  VoidDelegate();

    private void Window_Loaded(object sender, RoutedEventArgs e)
    {
        // Some other things to do here.
        System.Threading.ThreadPool.QueueUserWorkItem
                       (x => this.Dispatcher.Invoke(
                                  new VoidDelegate(SetFocus), null));
    }

    private void SetFocus()
    {
        MyControlIWantToSetFocusOn.Focus();
    }

Setting focus on WPF ComboBox not always working

1 Answers