QComboBox with only a icon on the toolbar, how?

I would like to make a combobox with QT and want to set it on the toolbar.

User should see on the Toolbar only icons, so this comboBox should show only the icon of an item on the toolbar.

But after the click on it, it pop up the sub-menu, which shows not only the icons but also the text of it at second column.

How can I sho开发者_JAVA百科w only icon in comboBox on the toolbar with QT 4.6.1?

Addendum: or with any QT version? (on Windows)