This section describes the window message processing performed by a toolbar. Because messages specific to toolbars are discussed elsewhere, they are not included here.
| Message | Default processing |
| WM_CHARTOITEM | Forwards this message to the parent window. |
| WM_COMMAND | Forwards this message to the parent window. |
| WM_CREATE | Allocates internal memory and graphics objects. It also initializes internal variables and data structures. |
| WM_DESTROY | Frees all memory and graphics objects previously allocated for the toolbar. |
| WM_DRAWITEM | Forwards this message to the parent window. |
| WM_LBUTTONDBLCLK | Forwards this message to the DefWindowProc function and returns the result. |
| WM_LBUTTONDOWN | Forwards this message to the tooltip control. If a button was clicked, it sets the state of the button and redraws it. It begins a drag operation if the toolbar has the CCS_ADJUSTABLE style and the SHIFT key is down (or the ALT key, if the toolbar has the TBSTYLE_ALTDRAG style). |
| WM_LBUTTONUP | Forwards this message to the tooltip control. If a button was clicked, it sets the state of the button and redraws it. It also ends the drag operation, if one is underway, and redraws the toolbar. |
| WM_MEASUREITEM | Forwards this message to the parent window. |
| WM_MOUSEMOVE | Forwards this message to the tooltip control. If a button has the mouse capture and the cursor moves out of the button rectangle, it redraws the button. It checks whether the toolbar has lost the mouse capture and, if it has, ends the drag operation. |
| WM_NCACTIVATE, WM_NCPAINT | Redraws the borders of the toolbar if the toolbar does not have the CCS_NODIVIDER style. Otherwise, it forwards the message to the DefWindowProc function. |
| WM_NOTIFY | Forwards the TTN_NEEDTEXT notification message from the tooltip control to the parent of the toolbar. |
| WM_PAINT | Draws the toolbar. If the wParam parameter is non-NULL, the control assumes that the value is an HDC and paints using that device context. |
| WM_SIZE | Recalculates the size and position of the toolbar and redraws it. |
| WM_SYSCOLORCHANGE | Updates the colors of the buttons and toolbar to march the system colors. |
| WM_VKEYTOITEM | Forwards this message to the parent window. |
| WM_WININICHANGE | Reinitializes internal variables that depend on system metric values. |