Wxpython. Is it possible to change layout in a running application? Selfmade listbox

[Soren]

Hi,

Id like to make my own special listbox.. I want to able (at the push
of a button) to add another item to my special listbox... each item is
a panel with a label, some buttons and maybe a text control.

I've tried adding a new panel object with the stuff i want to the
sizer i'm using for my listbox (which is a panel which can contain
other panels)... and then run update() and refresh() on everything...
But it doesn't work.. i see a panel appearing, but it's just a small
square in the corner of my "listbox" panel, and it only works the
first time... nothing new appears when I push the button again.

Is it at all possible to do this? Has anyone created something
similar? Does anyone know what i'm doing wrong?

Thanks,
Soren