accessing liststore of Combobox

["Mike Martin" <redtux1 googlemail com>]

Hi is there a way of accessing (removing) the contents of the
underlying liststore of a ComboBox constructed using simple text
methods

To Explain I have a combobox which depending on selection adds a
GtkEntry, GtkComboBox or GtkComoboBoxEntry, or directly runs a query.

Everything works fine except that when I choose the same criteria
twice (after selecting a second criteria) the list of values is
duplicated eg:

(This is for a DVB TV Viewer)

Combobox with values Start (ComboBoxEntry), Channel (ComboBox),
Category (ComboBox), Name (Entry)

1. Select Channel - a combobox appears with list of all available channels
2. Select start - a combobox appears with choice of start times
3. Select Channel - a combobox appears with a list of all available
channels listed twice

I am using $widget->remove to clear the control, but underlying
liststore is obviously getting appended. (tried destroy but get a
segfault)

Hope this is clear