Question

I need to reopen combobox list when a special item selected from the list. In this code I assume combo list will reopen when an item selected. It works if you use keyboard but I’ve got problem with the mouse.

        private void cbPredefinedReports_SelectionChanged(object sender, SelectionChangedEventArgs e)
        {
            cbPredefinedReports.IsDropDownOpen = true;
        }

How can I drop the list again when a user clicks an item?

Answer 1

Maybe this will help:

    <ComboBox Name="comboBox1" 
                    DropDownClosed="comboBox1_DropDownClosed" 
                    SelectionChanged="comboBox1_SelectionChanged" />

And your code behind

    private bool keepOpen = false;
    private void comboBox1_DropDownClosed(object sender, EventArgs e)
    {
        new Thread(() =>
        {
            comboBox1.Dispatcher.Invoke(new Action(() =>
            {
                // do your IF logic here
                if (keepOpen)
                {
                    comboBox1.IsDropDownOpen = true;
                    keepOpen = false;
                }
            }), null);
        }).Start();
    }

    private void comboBox1_SelectionChanged(object sender, SelectionChangedEventArgs e)
    {
        keepOpen = true;
    }

The reason you need a thread for this is because you can’t reopen the combobox in the DropDownClosed event, but you can do it in another thread. However, to update controlf in WPF from another thread, you need to invoke the Dispatcher. The above code does just what you asked.