Combobox suggestappend sort order

Question

If a combobox contains a source sorted as follows:

A_trip Monday
A_trip Tuesday
A_trip Wednesday
A_trip Thursday
B_trip Monday
B_trip Tuesday
B_trip Wednesday
B_trip Thursday

The drop-down box shows the contents sorted as shown.
If the box is cleared and the user types 'A' the result is:

A_trip Monday
A_trip Thursday
A_trip Tuesday
A_trip Wednesday

Is it possible to keep the same sort order as for the drop-down list?