There are nice solutions to the problem with combobox and prompt in WPF, but in my case I have mixed items -- image and text. So for example this solution (copied from https://stackoverflow.com/a/11671997/210342):
<ComboBox Name="MyComboBox"
IsEditable="True"
IsReadOnly="True"
Text="-- Select Team --" />
works fine as for prompt, but it has side effect, that when I select an item, the item in turn is not displayed correctly as selected -- it is presented in list OK, but after selection all combobox shows is System.Windows.Controls.ComboBoxItem
.
So how to have a prompt (I don't insist of fixing this approach) and properly displayed mixed items?