The tab control display area is the area of the control in which an application displays the current page. An application creates a child window or dialog box to display the current page, and then it sets the window size and position to fit the display area. You can use the TCM_ADJUSTRECT message to calculate a tab control's display area based on the dimensions of a specified rectangle or to calculate the dimensions of a rectangle given the coordinates of a display area.
Each tab in a tab control has a size and a position. You can set the size of tabs, retrieve the bounding rectangle of a tab, or determine which tab is located at a specified position.
For fixed-width and owner-drawn tab controls, you can set the exact width and height of tabs by using the TCM_SETITEMSIZE message. In other tab controls, you calculate each tab's size based on the icon and label for the tab. The tab control includes space for a border and an additional margin. You can set the thickness of the margin by using the TCM_SETPADDING message.
You use messages and styles to learn about tabs. You can determine the current bounding rectangle for a tab by using the TCM_GETITEMRECT message. You can determine which tab, if any, is at a specified location by using the TCM_HITTEST message. In a tab control with the TCS_MULTILINE style, you can determine the current number of rows of tabs by using the TCM_GETROWCOUNT message.