- When user type with the combobox selected, it will work on a temporary string to store the typed text;
- Each key typed leads to the combobox to be showed and updated
- If backspace is type, we update the filter
- Each key typed shows the combo box items, when the combobox is hidden, the filter is cleaned and the tooltip is hidden:
The class code and a sample application is below. I also added the source to my personal github, sent me PR to improve it and there are a lot of things to improve, like space and accents support.