Question

I develop an application but when I deploy that on client system then combo box is not opening

 <ComboBox Margin="5,0,0,0" Name="cbCOCountry" ItemsSource="{Binding Path=CountryCOCollection,Mode=TwoWay}" SelectedItem="{Binding Path=SelectedCOCountry,Mode=TwoWay}" VerticalAlignment="Center" Height="23" Grid.Row="1" Grid.Column="1">
                <ComboBox.ItemTemplate>
                    <DataTemplate>
                        <TextBlock Text="{Binding Path=CountryName}" VerticalAlignment="Center" Grid.Column="1" Margin="5,0,0,0"/>
                    </DataTemplate>
                </ComboBox.ItemTemplate>
            </ComboBox>

And I use the Whistler Blue theme in my application

Answer 1

I’ve seen this before. What OS are you using? There is a known issue on Windows XP machines:
http://social.msdn.microsoft.com/Forums/en-US/wpf/thread/333d3d93-8837-42b3-a0ea-1a577485daed/