WC_SPLITPANE programming reference
The splitpane control fully respects the PM control standards.
Both its
look and its behaviour can be easily changed via presentation
parameters or
the control specific styles, while the SPLITCTLDATA
data structure allows
full control on its initial values on window creation or in dialog
scripts.
Besides that, a rich set of function-like
macros provides an easy way
to modify or retrieve the state of the control and its components after
the window creation.