CreateComboBox(): specify the default height to be the same as in constructor
tab demo: extended the demo to test/show other properties of PageControl
pagecontrol: tab height is not hard-coded any more.
tabs: ensures that scroll buttons are not visible
tabtest: Adds a debug label to tabsheet four to verify the tabsheet height value
tabs: Tab height is now correctly drawn - no hard-coded 21px height any more
tabs: Fixed the painting of tabs when positioned at tpBottom.

* The text was not at the correct position (to high)
* The tab height was not the same as when tpTop is used