[gtkada] Problems with text only combo box

[Rob Groen]

Hello,

When trying to use text only combo boxes I have the following problems
- When removing the active element from the combo box with Remove_Text 
the program crashes with "raised INTERFACES.C.STRINGS.DEREFERENCE_ERROR 
: i-cstrin.adb:206"
- when trying to clear the data by using Get_Model on the combo box en 
Clear on the model I get the same error;
- trying to workaround this problem by creating a combo box with a 
Gtk_List_Store as model I can iterate over the model and the data is 
there, but nothing is shown in the widget, and also nothing is shown in 
the popdown.

Any help is welcome

Regards,
Rob Groen