This function associates the presentation parameter attribute identified by idAttrType with the window hwnd. If the attribute already exists for the window, its value is changed to the new value specified by pAttrValue. If the attribute does not exist, it is added to the window's presentation parameters, with the specified value. (See also WinQueryPresParam and WinRemovePresParam).

When a presentation parameter is set, a WM_PRESPARAMCHANGED message is sent to all windows owned by the window calling the WinSetPresParam function.

When switching from using color indexes to using RGB color values, you must call GpiCreateLogColorTable with the LCOLF_RGB parameter. Otherwise, this function will treat the RGB color passed as an index into a color table, rather than as an absolute color value.