XcupGetReservedColormapEntries - list colormap entries reserved by the system
cc [ flag ... ] file ... -lXext [ library ... ]
#include <X11/extensions/Xcup.h>
Status XcupGetReservedColormapEntries(Display *display,
int screen, XColor **colors_out, int *ncolors);
  - display
- Specifies the connection to the X server.
- screen
- Screen number on the host server.
- colors_out
- Returns the values reserved by the server.
- ncolors
- Returns the number of items in colors_out.
The XcupGetReservedColormapEntries function returns a list of colormap
  entries (pixels) that are reserved by the system. This list will, at a
  minimum, contain entries for the BlackPixel and WhitePixel of the specified
  screen. Use XFree to free colors_out.To minimize colormap flash, an application which installs its own
    private colormap should query the special colors by calling
    XCupGetReservedColormapEntries, and can then store those entries (in
    the proper location) in its private colormap using
  XCupStoreColors.
XcupQueryVersion(3Xext), XcupStoreColors(3Xext),
  XFree(3X11),
Colormap Utilization Policy and Extension