Follow along with the video below to see how to install our site as a web app on your home screen.
Anmerkung: This feature currently requires accessing the site using the built-in Safari browser.
myComboBox.SelectedIndex = -1;
Ich würde es irgend wie so versuchen:
combobox1.Text = String.Empty;
combobox1.SelectedText = combobox1.Text;