Default Up-Down Controls Message Processing

This section describes the window message processing performed by an up-down control.

Message Processing performed
WM_CREATE Allocates and initializes a private data structure and saves its address as window data.
WM_DESTROY Frees data allocated during WM_CREATE processing.
WM_ENABLE Invalidates the window.
WM_KEYDOWN Changes the current position in the case of an

UP ARROW or DOWN ARROW key.
WM_KEYUP Ends changing the position.
WM_LBUTTONDOWN Captures the mouse. If the buddy window is an edit control or list box, it sets the focus to the buddy window. If the mouse is over the up or down button, it begins changing the position and sets a timer.
WM_LBUTTONUP Ends changing the position and releases the mouse capture if the up-down control has captured the mouse. If the buddy window is an edit control, it selects all the text in the edit control.
WM_PAINT Paints the up-down control. If the wParam parameter is non-NULL, the control assumes that the value is an HDC and paints using that device context.
WM_TIMER Changes the current position if the mouse is being held down over a button and a sufficient interval has elapsed.