private void ComboBox_DropDownClosed(object sender, EventArgs e) { var selectedTheme = new AppearanceViewModel().GetSelectedTheme(); selectedTheme = ((FirstFloor.ModernUI.Presentation.Displayable)(selectedTheme)).DisplayName; if (selectedTheme.ToString() == "light") { var cb = (ComboBox)sender; cb.Foreground = Brushes.Black; } else { var cb = (ComboBox)sender; cb.Foreground = Brushes.WhiteSmoke; } }