Signals for combobox entry

["Mike Martin" <redtux1 googlemail com>]

Hi

I have a drop-down box which adds to the display depending on selection

Combobox
Comboboxentry
Entry

However I am having problems with signals with the combobox entry

the actions are

Combobox = changed
Entry = Keypress event (tab/entry/return)

however for the comboboxentry, changed isnt acceptable as it fires on
every change (runs database query so not good performance)

No keypress events seem to be generated for CBE so are there any other
approaches that will fire only when whole field has been updated?