Keyboard response when defining a new column for a table

Is there any particular reason why, when defining a new column in a
table, in the field "Data type" the entry cannot be selected with the
keyboard? For example, when defining a serial type, which happens almost
always when defining a new table, typing "s" does not take me to the s*
in the list? Not a big deal since scrolling down gets to the bottom of
the list after a few moments, but it is inconvenient since one hand has
to move from keyboard to mouse.

Another curiosity of this field is that if user begins by using the page
up, down, home, end or up down arrows, subsequently the backspace and
regular keys do not work. The field looks like a combo box, but it does
not behave like one.