The TB_SETBUTTONSIZE sets the size of the buttons to be added to a toolbar.
TB_SETBUTTONSIZE
wParam = 0;
lParam = (LPARAM) MAKELONG(dxButton, dyButton)
Parameters
dxButton
Width, in pixels, of the buttons.
dyButton
Height, in pixels, of the buttons.
Return Values
Returns TRUE if successful or FALSE otherwise.
Remarks
The size can be set only before adding any buttons to the toolbar. If an application does not explicitly set the button size, the size defaults to 24 by 22 pixels.