Glamour Tabs not updated when update is called

Not sure if this is a bug, but here goes.
Looking through the Glamour examples in Pharo4 I come across the Updateable Browser example.
This example has a line that, when the collection is greater than 1, shows a list tab, the title of which is List, col size printString.
This indeed comes up and shows: 'List: 2' but if you continue to add, it doesn't change. The text will change but not the title.
I came across this when I couldn't get my browser to add tabs, even though entity gets updated.
Example from Glamour below.

| browser collection|
    collection := GLMAnnouncingCollection new.
    collection add: 1.
    browser := GLMTabulator new.
    browser column: #preview.
    browser
        act: [:b | b entity add: (b entity size + 1). b update ]    
        icon: GLMUIThemeExtraIcons glamorousAdd
        entitled: 'Add an item in the collection'.
    browser
        act: [:b | b entity removeLast. b update ]
        icon: GLMUIThemeExtraIcons glamorousRemove
        entitled: 'Remove last item from the collection'.
    browser
        updateOn: GLMItemAdded from: #yourself;
        updateOn: GLMItemRemoved from: #yourself.
    browser transmit to: #preview; andShow: [ :a |
        a list
            title: [:col | 'List: ', col size printString ]; "This isn't updating"
            when: [:col | col size > 1 ].
        a text title: 'Text';
            format: [:col | 'Current collection: ', col printString, '. Add more items to show the list'] ].
    browser openOn: collection

KR