>Well, I have a toolbar with 10 buttons on it and a hidden combobox. The toolbar height is 30. When the user clicks on one of the buttons, I hide all the buttons and make the combo box visible. This automatically increases the height of the toolbar to about 100+. The height of my combo box is set to 25. I've tried resetting the height of the toolbar but it ignores the change.

Try to decrease the height of the combobox so toolbat height doesn't change when combo becames visible. You can also try to make the combo visible first and than hide buttons.