Autocomplete Data Validation Combo Box
 

I refer to the code in http://www.contextures.com/xlDataVal11.html for
auto-completion of data validation using a combo box.

I would like to call up the combobox in a single click, instead of a double
click as per the current code.

Also, I am able to enter an invalid value (ie, value not from the data
validation) list in the combo box.

Is it possible to modify the code to

1. Call up the combobox in a single click
2. Prevent an invalid input, whether by direct entry or copy/paste (value or
all) into the cell having the validation

Thanks in advance