Owner-draw tabs can display objects other than strings, such as graphical images. Owner-draw tabs require more programming, however, because the application needs information on how to render the image for each tab in the tab set control. 

Each time an item is displayed in an owner-drawn tab, two events occur. The first is the OnMeasureTab event. In the OnMeasureTab event handler, you write the code that calculates the width of the tab needed to hold the text or graphical image. After the OnMeasureTab event, the OnDrawTab event occurs. The code you write for the OnDrawTab event draws the tab and its contents using the width found with the OnMeasureTab event and the height specified as the value of the TabHeight property.

TabHeight 

OnDrawTab 

OnMeasureTab