1 files changed, 1010 insertions, 0 deletions

diff --git a/xc/extras/Mesa/src-glut/glut_menu.c b/xc/extras/Mesa/src-glut/glut_menu.c
new file mode 100644
index 000000000..a959492b1
--- /dev/null
+++ b/xc/extras/Mesa/src-glut/glut_menu.c
@@ -0,0 +1,1010 @@
+
+/* Copyright (c) Mark J. Kilgard, 1994, 1997. */
+
+/* This program is freely distributable without licensing fees
+   and is provided without guarantee or warrantee expressed or
+   implied. This program is -not- in the public domain. */
+
+/* The Win32 GLUT file win32_menu.c completely re-implements all
+   the menuing functionality implemented.  This file is used only by
+   the X Window System version of GLUT. */
+
+#include <stdlib.h>
+#include <string.h>
+#include <stdio.h>
+#include <errno.h>
+#include <assert.h>
+
+#include <unistd.h>
+#include <X11/Xlib.h>
+#include <X11/cursorfont.h>  /* for XC_arrow */
+
+#include "glutint.h"
+#include "layerutil.h"
+
+void (CDECL *__glutMenuStatusFunc) (int, int, int);
+GLUTmenuItem *__glutItemSelected;
+GLUTmenu **__glutMenuList = NULL;
+
+static int menuListSize = 0;
+static XFontStruct *menuFont = NULL;
+static Cursor menuCursor;
+static Colormap menuColormap;
+static Visual *menuVisual;
+static int menuDepth;
+static int fontHeight;
+static GC blackGC, grayGC, whiteGC;
+static unsigned long menuBlack, menuWhite, menuGray;
+static unsigned long useSaveUnders;
+
+/* A replacement for XAllocColor (originally by Brian Paul).
+   This  function should never fail to allocate a color.  When
+   XAllocColor fails, we return the nearest matching color.  If
+   we have to allocate many colors this function isn't a great
+   solution; the XQueryColors() could be done just once.  */
+static void
+noFaultXAllocColor(Display * dpy, Colormap cmap, int cmapSize,
+  XColor * color)
+{
+  XColor *ctable, subColor;
+  int i, bestmatch;
+  double mindist;       /* 3*2^16^2 exceeds 32-bit long int
+                           precision. */
+
+  for (;;) {
+    /* First try just using XAllocColor. */
+    if (XAllocColor(dpy, cmap, color)) {
+      return;
+    }
+
+    /* Retrieve color table entries. */
+    /* XXX alloca canidate. */
+    ctable = (XColor *) malloc(cmapSize * sizeof(XColor));
+    for (i = 0; i < cmapSize; i++)
+      ctable[i].pixel = i;
+    XQueryColors(dpy, cmap, ctable, cmapSize);
+
+    /* Find best match. */
+    bestmatch = -1;
+    mindist = 0.0;
+    for (i = 0; i < cmapSize; i++) {
+      double dr = (double) color->red - (double) ctable[i].red;
+      double dg = (double) color->green - (double) ctable[i].green;
+      double db = (double) color->blue - (double) ctable[i].blue;
+      double dist = dr * dr + dg * dg + db * db;
+      if (bestmatch < 0 || dist < mindist) {
+        bestmatch = i;
+        mindist = dist;
+      }
+    }
+
+    /* Return result. */
+    subColor.red = ctable[bestmatch].red;
+    subColor.green = ctable[bestmatch].green;
+    subColor.blue = ctable[bestmatch].blue;
+    free(ctable);
+    if (XAllocColor(dpy, cmap, &subColor)) {
+      *color = subColor;
+      return;
+    }
+    /* Extremely unlikely, but possibly color was deallocated
+       and reallocated by someone else before we could
+       XAllocColor the color cell we located.  If so, loop
+       again... */
+  }
+}
+
+static int
+ifSunCreator(void)
+{
+  char *xvendor, *glvendor, *renderer;
+  int isSunCreator = 0; /* Until proven that it is. */
+  int savedDisplayMode = 0;
+  char *savedDisplayString = 0;
+  GLUTwindow *window;
+
+#define VENDOR_SUN "Sun Microsystems"
+#define RENDERER_CREATOR "Creator"
+
+  /* Check the X vendor string first.  It is easier to check
+     than the OpenGL vendor and renderer strings since it
+     doesn't require a valid OpenGL rendering context.  Bail
+     early if not connected to a Sun. */
+  xvendor = ServerVendor(__glutDisplay);
+  if (!strncmp(xvendor, VENDOR_SUN, sizeof(VENDOR_SUN) - 1)) {
+
+    /* We need a valid current OpenGL rendering context to be
+       able to call glGetString successfully.  If there is not
+       a current window, set up a temporary one just to call
+       glGetString with (gag, expensive). */
+    if (__glutCurrentWindow) {
+      window = NULL;
+    } else {
+      savedDisplayMode = __glutDisplayMode;
+      savedDisplayString = __glutDisplayString;
+      __glutDisplayMode = GLUT_RGB | GLUT_SINGLE;
+      __glutDisplayString = NULL;
+      window = __glutCreateWindow(NULL, 0, 0, 1, 1, 0);
+    }
+
+    glvendor = (char *) glGetString(GL_VENDOR);
+    if (!strncmp(glvendor, VENDOR_SUN, sizeof(VENDOR_SUN) - 1)) {
+      renderer = (char *) glGetString(GL_RENDERER);
+      if (!strncmp(renderer, RENDERER_CREATOR, sizeof(RENDERER_CREATOR) - 1)) {
+        isSunCreator = 1;
+      }
+    }
+    /* Destroy the temporary window for glGetString if one
+       needed to be created. */
+    if (window) {
+      __glutDestroyWindow(window, window);
+      __glutDisplayMode = savedDisplayMode;
+      __glutDisplayString = savedDisplayString;
+    }
+  }
+  return isSunCreator;
+}
+
+static void
+menuVisualSetup(void)
+{
+  XLayerVisualInfo template, *visual, *overlayVisuals;
+  XColor color;
+  Status status;
+  Bool presumablyMesa;
+  int layer, nVisuals, i, dummy;
+  unsigned long *placeHolders = NULL;
+  int numPlaceHolders = 0;
+  Bool allocateHigh;
+
+  allocateHigh = ifSunCreator();
+
+  /* Start with the highest overlay layer and work down.  I
+     don't think any hardware has more than 3 overlay layers. */
+  for (layer = 3; layer > 0; layer--) {
+    template.layer = layer;
+    template.vinfo.screen = __glutScreen;
+    overlayVisuals = __glutXGetLayerVisualInfo(__glutDisplay,
+      VisualScreenMask | VisualLayerMask, &template, &nVisuals);
+    if (overlayVisuals) {
+      /* First, check if the default visual is in this layer.
+         If the default visual is in this layer, we try to use
+         it since it has pre-defined black and white pixels and 
+
+         using the default visual will probably minimize
+         colormap flashing problems. Suggested by Thomas Roell
+         (thomas@xig.com). */
+      for (i = 0; i < nVisuals; i++) {
+        visual = &overlayVisuals[i];
+        if (visual->vinfo.colormap_size >= 3) {
+          /* Compare visual IDs just to be safe. */
+          if (visual->vinfo.visual->visualid == DefaultVisual(__glutDisplay, __glutScreen)->visualid) {
+            /* Settle for default visual. */
+            menuVisual = DefaultVisual(__glutDisplay, __glutScreen);
+            menuDepth = DefaultDepth(__glutDisplay, __glutScreen);
+            menuColormap = DefaultColormap(__glutDisplay, __glutScreen);
+            menuBlack = BlackPixel(__glutDisplay, __glutScreen);
+            menuWhite = WhitePixel(__glutDisplay, __glutScreen);
+            color.red = color.green = color.blue = 0xaa00;
+            noFaultXAllocColor(__glutDisplay, menuColormap,
+              menuVisual->map_entries, &color);
+            menuGray = color.pixel;
+            useSaveUnders = 0;
+            XFree(overlayVisuals);
+            return;
+          }
+        }
+      }
+      for (i = 0; i < nVisuals; i++) {
+        visual = &overlayVisuals[i];
+        if (visual->vinfo.colormap_size >= 3) {
+          if (allocateHigh) {
+            /* For Sun's Creator graphics, try to force the
+               read-only colors to the high end of the colormap
+               by first allocating read-write place-holder cells
+               for all but the last three cells.  This helps
+               avoid colormap flashing problems. */
+            numPlaceHolders = visual->vinfo.colormap_size - 3;
+            if (numPlaceHolders > 0) {
+              placeHolders = (unsigned long *)
+                malloc(numPlaceHolders * sizeof(unsigned long));
+              /* A malloc failure would be harmless. */
+            }
+          }
+          menuColormap = XCreateColormap(__glutDisplay, __glutRoot,
+            visual->vinfo.visual, AllocNone);
+          if (placeHolders) {
+            /* Again for Sun's Creator graphics, do the actual
+               read-write place-holder cell allocation. */
+            status = XAllocColorCells(__glutDisplay, menuColormap, False, 0, 0,
+              placeHolders, numPlaceHolders);
+            if (!status) {
+              XFreeColormap(__glutDisplay, menuColormap);
+              free(placeHolders);
+              continue;
+            }
+          }
+          /* Allocate overlay colormap cells in defined order:
+             gray, black, white to match the IRIS GL allocation
+             scheme.  Increases likelihood of less overlay
+             colormap flashing. */
+          /* XXX Nice if these 3 AllocColor's could be done in
+             one protocol round-trip. */
+          color.red = color.green = color.blue = 0xaa00;
+          status = XAllocColor(__glutDisplay,
+            menuColormap, &color);
+          if (!status) {
+            XFreeColormap(__glutDisplay, menuColormap);
+            if (placeHolders) {
+              free(placeHolders);
+            }
+            continue;
+          }
+          menuGray = color.pixel;
+          color.red = color.green = color.blue = 0x0000;
+          status = XAllocColor(__glutDisplay,
+            menuColormap, &color);
+          if (!status) {
+            XFreeColormap(__glutDisplay, menuColormap);
+            if (placeHolders) {
+              free(placeHolders);
+            }
+            continue;
+          }
+          menuBlack = color.pixel;
+          color.red = color.green = color.blue = 0xffff;
+          status = XAllocColor(__glutDisplay,
+            menuColormap, &color);
+          if (!status) {
+            XFreeColormap(__glutDisplay, menuColormap);
+            if (placeHolders) {
+              free(placeHolders);
+            }
+            continue;
+          }
+          if (placeHolders) {
+            /* Now free the placeholder cells. */
+            XFreeColors(__glutDisplay, menuColormap,
+              placeHolders, numPlaceHolders, 0);
+            free(placeHolders);
+          }
+          menuWhite = color.pixel;
+          menuVisual = visual->vinfo.visual;
+          menuDepth = visual->vinfo.depth;
+          /* If using overlays, do not request "save unders". */
+          useSaveUnders = 0;
+          XFree(overlayVisuals);
+          return;
+        }
+      }
+      XFree(overlayVisuals);
+    }
+  }
+  /* Settle for default visual. */
+  menuVisual = DefaultVisual(__glutDisplay, __glutScreen);
+  menuDepth = DefaultDepth(__glutDisplay, __glutScreen);
+  menuColormap = DefaultColormap(__glutDisplay, __glutScreen);
+  menuBlack = BlackPixel(__glutDisplay, __glutScreen);
+  menuWhite = WhitePixel(__glutDisplay, __glutScreen);
+  color.red = color.green = color.blue = 0xaa00;
+  noFaultXAllocColor(__glutDisplay, menuColormap,
+    menuVisual->map_entries, &color);
+  menuGray = color.pixel;
+
+  /* When no overlays are supported, we would like to use X
+     "save unders" to avoid exposes to windows obscured by
+     pop-up menus.  However, OpenGL's direct rendering support
+     means OpenGL interacts poorly with X backing store and
+     save unders.  X servers do not (in implementation
+     practice) redirect OpenGL rendering destined to obscured
+     window regions into backing store.
+
+     Implementation solutions exist for this problem, but they
+     are expensive and high-end OpenGL implementations
+     typically provide fast rendering and/or overlays to
+     obviate the problem associated of user interfaces (pop-up
+     menus) forcing redraws of complex normal plane scenes.
+     (See support for overlays pop-up menus above.)
+
+     Mesa 3D, however, does not support direct rendering.
+     Overlays are often unavailable to Mesa, and Mesa is also
+     relatively slow.  For these reasons, Mesa-rendering GLUT
+     programs can and should use X save unders.
+
+     Look for the GLX extension.  If _not_ supported, we are
+     presumably using Mesa so enable save unders. */
+
+  presumablyMesa = !XQueryExtension(__glutDisplay, "GLX",
+    &dummy, &dummy, &dummy);
+
+  if (presumablyMesa) {
+    useSaveUnders = CWSaveUnder;
+  } else {
+    useSaveUnders = 0;
+  }
+}
+
+static void
+menuSetup(void)
+{
+  if (menuFont) {
+    /* MenuFont overload to indicate menu initalization. */
+    return;
+  }
+  menuFont = XLoadQueryFont(__glutDisplay,
+    "-*-helvetica-bold-o-normal--14-*-*-*-p-*-iso8859-1");
+  if (!menuFont) {
+    /* Try back up font. */
+    menuFont = XLoadQueryFont(__glutDisplay, "fixed");
+  }
+  if (!menuFont) {
+    __glutFatalError("could not load font.");
+  }
+  menuVisualSetup();
+  fontHeight = menuFont->ascent + menuFont->descent;
+  menuCursor = XCreateFontCursor(__glutDisplay, XC_arrow);
+}
+
+static void
+menuGraphicsContextSetup(Window win)
+{
+  XGCValues gcvals;
+
+  if (blackGC != None) {
+    return;
+  }
+  gcvals.font = menuFont->fid;
+  gcvals.foreground = menuBlack;
+  blackGC = XCreateGC(__glutDisplay, win,
+    GCFont | GCForeground, &gcvals);
+  gcvals.foreground = menuGray;
+  grayGC = XCreateGC(__glutDisplay, win, GCForeground, &gcvals);
+  gcvals.foreground = menuWhite;
+  whiteGC = XCreateGC(__glutDisplay, win, GCForeground, &gcvals);
+}
+
+void
+__glutSetMenu(GLUTmenu * menu)
+{
+  __glutCurrentMenu = menu;
+}
+
+static void
+unmapMenu(GLUTmenu * menu)
+{
+  if (menu->cascade) {
+    unmapMenu(menu->cascade);
+    menu->cascade = NULL;
+  }
+  menu->anchor = NULL;
+  menu->highlighted = NULL;
+  XUnmapWindow(__glutDisplay, menu->win);
+}
+
+static void
+finishMenu(Window win, int x, int y)
+{
+  Window dummy;
+  int rc;
+
+  unmapMenu(__glutMappedMenu);
+  XUngrabPointer(__glutDisplay, CurrentTime);
+
+  /* Popping up an overlay popup menu will install its own
+     colormap.  If the window associated with the menu has an
+     overlay, install that window's overlay colormap so the
+     overlay isn't left using the popup menu's colormap. */
+  if (__glutMenuWindow->overlay) {
+    XInstallColormap(__glutDisplay,
+      __glutMenuWindow->overlay->colormap->cmap);
+  }
+
+  /* This XFlush is needed to to make sure the pointer is
+     really ungrabbed when the application's menu callback is
+     called. Otherwise, a deadlock might happen because the
+     application may try to read from an terminal window, but
+     yet the ungrab hasn't really happened since it hasn't been
+     flushed out. */
+  XFlush(__glutDisplay);
+
+  if (__glutMenuStatusFunc) {
+    if (win != __glutMenuWindow->win) {
+      /* The button release may have occurred in a window other
+         than the window requesting the pop-up menu (for
+         example, one of the submenu windows).  In this case, we
+         need to translate the coordinates into the coordinate
+         system of the window associated with the window. */
+      rc = XTranslateCoordinates(__glutDisplay, win, __glutMenuWindow->win,
+        x, y, &x, &y, &dummy);
+      assert(rc != False);  /* Will always be on same screen. */
+    }
+    __glutSetWindow(__glutMenuWindow);
+    __glutSetMenu(__glutMappedMenu);
+
+    /* Setting __glutMappedMenu to NULL permits operations that
+       change menus or destroy the menu window again. */
+    __glutMappedMenu = NULL;
+
+    __glutMenuStatusFunc(GLUT_MENU_NOT_IN_USE, x, y);
+  }
+  /* Setting __glutMappedMenu to NULL permits operations that
+     change menus or destroy the menu window again. */
+  __glutMappedMenu = NULL;
+
+  /* If an item is selected and it is not a submenu trigger,
+     generate menu callback. */
+  if (__glutItemSelected && !__glutItemSelected->isTrigger) {
+    __glutSetWindow(__glutMenuWindow);
+    /* When menu callback is triggered, current menu should be
+       set to the callback menu. */
+    __glutSetMenu(__glutItemSelected->menu);
+    __glutItemSelected->menu->select(
+      __glutItemSelected->value);
+  }
+  __glutMenuWindow = NULL;
+}
+
+#define MENU_BORDER 1
+#define MENU_GAP 2
+#define MENU_ARROW_GAP 6
+#define MENU_ARROW_WIDTH 8
+
+static void
+mapMenu(GLUTmenu * menu, int x, int y)
+{
+  XWindowChanges changes;
+  unsigned int mask;
+  int subMenuExtension, num;
+
+  /* If there are submenus, we need to provide extra space for
+     the submenu pull arrow.  */
+  if (menu->submenus > 0) {
+    subMenuExtension = MENU_ARROW_GAP + MENU_ARROW_WIDTH;
+  } else {
+    subMenuExtension = 0;
+  }
+
+  changes.stack_mode = Above;
+  mask = CWStackMode | CWX | CWY;
+  /* If the menu isn't managed (ie, validated so all the
+     InputOnly subwindows are the right size), do so.  */
+  if (!menu->managed) {
+    GLUTmenuItem *item;
+
+    item = menu->list;
+    num = menu->num;
+    while (item) {
+      XWindowChanges itemupdate;
+
+      itemupdate.y = (num - 1) * fontHeight + MENU_GAP;
+      itemupdate.width = menu->pixwidth;
+      itemupdate.width += subMenuExtension;
+      XConfigureWindow(__glutDisplay, item->win,
+        CWWidth | CWY, &itemupdate);
+      item = item->next;
+      num--;
+    }
+    menu->pixheight = MENU_GAP +
+      fontHeight * menu->num + MENU_GAP;
+    changes.height = menu->pixheight;
+    changes.width = MENU_GAP +
+      menu->pixwidth + subMenuExtension + MENU_GAP;
+    mask |= CWWidth | CWHeight;
+    menu->managed = True;
+  }
+  /* Make sure menu appears fully on screen. */
+  if (y + menu->pixheight >= __glutScreenHeight) {
+    changes.y = __glutScreenHeight - menu->pixheight;
+  } else {
+    changes.y = y;
+  }
+  if (x + menu->pixwidth + subMenuExtension >=
+    __glutScreenWidth) {
+    changes.x = __glutScreenWidth -
+      menu->pixwidth + subMenuExtension;
+  } else {
+    changes.x = x;
+  }
+
+  /* Rember where the menu is placed so submenus can be
+     properly placed relative to it. */
+  menu->x = changes.x;
+  menu->y = changes.y;
+
+  XConfigureWindow(__glutDisplay, menu->win, mask, &changes);
+  XInstallColormap(__glutDisplay, menuColormap);
+  /* XXX The XRaiseWindow below should not be necessary because
+     the XConfigureWindow requests an Above stack mode (same as
+     XRaiseWindow), but some Sun users complained this was still
+     necessary.  Probably some window manager or X server bug on
+     these machines?? */
+  XRaiseWindow(__glutDisplay, menu->win);
+  XMapWindow(__glutDisplay, menu->win);
+}
+
+static void
+startMenu(GLUTmenu * menu, GLUTwindow * window,
+  int x, int y, int x_win, int y_win)
+{
+  int grab;
+
+  assert(__glutMappedMenu == NULL);
+  grab = XGrabPointer(__glutDisplay, __glutRoot, True,
+    ButtonPressMask | ButtonReleaseMask,
+    GrabModeAsync, GrabModeAsync,
+    __glutRoot, menuCursor, CurrentTime);
+  if (grab != GrabSuccess) {
+    /* Somebody else has pointer grabbed, ignore menu
+       activation. */
+    return;
+  }
+  __glutMappedMenu = menu;
+  __glutMenuWindow = window;
+  __glutItemSelected = NULL;
+  if (__glutMenuStatusFunc) {
+    __glutSetMenu(menu);
+    __glutSetWindow(window);
+    __glutMenuStatusFunc(GLUT_MENU_IN_USE, x_win, y_win);
+  }
+  mapMenu(menu, x, y);
+}
+
+static void
+paintSubMenuArrow(Window win, int x, int y)
+{
+  XPoint p[5];
+
+  p[0].x = p[4].x = x;
+  p[0].y = p[4].y = y - menuFont->ascent + 1;
+  p[1].x = p[0].x + MENU_ARROW_WIDTH - 1;
+  p[1].y = p[0].y + (menuFont->ascent / 2) - 1;
+  p[2].x = p[1].x;
+  p[2].y = p[1].y + 1;
+  p[3].x = p[0].x;
+  p[3].y = p[0].y + menuFont->ascent - 2;
+  XFillPolygon(__glutDisplay, win,
+    whiteGC, p, 4, Convex, CoordModeOrigin);
+  XDrawLines(__glutDisplay, win, blackGC, p, 5, CoordModeOrigin);
+}
+
+static void
+paintMenuItem(GLUTmenuItem * item, int num)
+{
+  Window win = item->menu->win;
+  GC gc;
+  int y;
+  int subMenuExtension;
+
+  if (item->menu->submenus > 0) {
+    subMenuExtension = MENU_ARROW_GAP + MENU_ARROW_WIDTH;
+  } else {
+    subMenuExtension = 0;
+  }
+  if (item->menu->highlighted == item) {
+    gc = whiteGC;
+  } else {
+    gc = grayGC;
+  }
+  y = MENU_GAP + fontHeight * num - menuFont->descent;
+  XFillRectangle(__glutDisplay, win, gc,
+    MENU_GAP, y - fontHeight + menuFont->descent,
+    item->menu->pixwidth + subMenuExtension, fontHeight);
+  XDrawString(__glutDisplay, win, blackGC,
+    MENU_GAP, y, item->label, item->len);
+  if (item->isTrigger) {
+    paintSubMenuArrow(win,
+      item->menu->pixwidth + MENU_ARROW_GAP + 1, y);
+  }
+}
+
+static void
+paintMenu(GLUTmenu * menu)
+{
+  GLUTmenuItem *item;
+  int i = menu->num;
+  int y = MENU_GAP + fontHeight * i - menuFont->descent;
+
+  item = menu->list;
+  while (item) {
+    if (item->menu->highlighted == item) {
+      paintMenuItem(item, i);
+    } else {
+      /* Quick render of the menu item; assume background
+         already cleared to gray. */
+      XDrawString(__glutDisplay, menu->win, blackGC,
+        2, y, item->label, item->len);
+      if (item->isTrigger) {
+        paintSubMenuArrow(menu->win,
+          menu->pixwidth + MENU_ARROW_GAP + 1, y);
+      }
+    }
+    i--;
+    y -= fontHeight;
+    item = item->next;
+  }
+}
+
+static GLUTmenuItem *
+getMenuItem(GLUTmenu * menu, Window win, int *which)
+{
+  GLUTmenuItem *item;
+  int i;
+
+  if (menu->searched) {
+    __glutFatalError("submenu infinite loop detected");
+  }
+  menu->searched = True;
+  i = menu->num;
+  item = menu->list;
+  while (item) {
+    if (item->win == win) {
+      *which = i;
+      menu->searched = False;
+      return item;
+    }
+    if (item->isTrigger) {
+      GLUTmenuItem *subitem;
+
+      subitem = __glutGetMenuItem(__glutMenuList[item->value],
+        win, which);
+      if (subitem) {
+        menu->searched = False;
+        return subitem;
+      }
+    }
+    i--;
+    item = item->next;
+  }
+  menu->searched = False;
+  return NULL;
+}
+
+static int
+getMenuItemIndex(GLUTmenuItem * item)
+{
+  int count = 0;
+
+  while (item) {
+    count++;
+    item = item->next;
+  }
+  return count;
+}
+
+static GLUTmenu *
+getMenu(Window win)
+{
+  GLUTmenu *menu;
+
+  menu = __glutMappedMenu;
+  while (menu) {
+    if (win == menu->win) {
+      return menu;
+    }
+    menu = menu->cascade;
+  }
+  return NULL;
+}
+
+static GLUTmenu *
+getMenuByNum(int menunum)
+{
+  if (menunum < 1 || menunum > menuListSize) {
+    return NULL;
+  }
+  return __glutMenuList[menunum - 1];
+}
+
+static int
+getUnusedMenuSlot(void)
+{
+  int i;
+
+  /* Look for allocated, unused slot. */
+  for (i = 0; i < menuListSize; i++) {
+    if (!__glutMenuList[i]) {
+      return i;
+    }
+  }
+  /* Allocate a new slot. */
+  menuListSize++;
+  if (__glutMenuList) {
+    __glutMenuList = (GLUTmenu **)
+      realloc(__glutMenuList, menuListSize * sizeof(GLUTmenu *));
+  } else {
+    /* XXX Some realloc's do not correctly perform a malloc
+       when asked to perform a realloc on a NULL pointer,
+       though the ANSI C library spec requires this. */
+    __glutMenuList = (GLUTmenu **) malloc(sizeof(GLUTmenu *));
+  }
+  if (!__glutMenuList) {
+    __glutFatalError("out of memory.");
+  }
+  __glutMenuList[menuListSize - 1] = NULL;
+  return menuListSize - 1;
+}
+
+void
+__glutMenuModificationError(void)
+{
+  /* XXX Remove the warning after GLUT 3.0. */
+  __glutWarning("The following is a new check for GLUT 3.0; update your code.");
+  __glutFatalError("menu manipulation not allowed while menus in use.");
+}
+
+
+static void
+menuItemEnterOrLeave(GLUTmenuItem * item,
+  int num, int type)
+{
+  int alreadyUp = 0;
+
+  if (type == EnterNotify) {
+    GLUTmenuItem *prevItem = item->menu->highlighted;
+
+    if (prevItem && prevItem != item) {
+      /* If there's an already higlighted item in this menu
+         that is different from this one (we could be
+         re-entering an item with an already cascaded
+         submenu!), unhighlight the previous item. */
+      item->menu->highlighted = NULL;
+      paintMenuItem(prevItem, getMenuItemIndex(prevItem));
+    }
+    item->menu->highlighted = item;
+    __glutItemSelected = item;
+    if (item->menu->cascade) {
+      if (!item->isTrigger) {
+        /* Entered a menu item that is not a submenu trigger,
+           so pop down the current submenu cascade of this
+           menu.  */
+        unmapMenu(item->menu->cascade);
+        item->menu->cascade = NULL;
+      } else {
+        GLUTmenu *submenu = __glutMenuList[item->value];
+
+        if (submenu->anchor == item) {
+          /* We entered the submenu trigger for the submenu
+             that is already up, so don't take down the
+             submenu.  */
+          alreadyUp = 1;
+        } else {
+          /* Submenu already popped up for some other submenu
+             item of this menu; need to pop down that other
+             submenu cascade.  */
+          unmapMenu(item->menu->cascade);
+          item->menu->cascade = NULL;
+        }
+      }
+    }
+    if (!alreadyUp) {
+      /* Make sure the menu item gets painted with
+         highlighting. */
+      paintMenuItem(item, num);
+    } else {
+      /* If already up, should already be highlighted.  */
+    }
+  } else {
+    /* LeaveNotify: Handle leaving a menu item...  */
+    if (item->menu->cascade &&
+      item->menu->cascade->anchor == item) {
+      /* If there is a submenu casacaded from this item, do not
+         change the highlighting on this item upon leaving. */
+    } else {
+      /* Unhighlight this menu item.  */
+      item->menu->highlighted = NULL;
+      paintMenuItem(item, num);
+    }
+    __glutItemSelected = NULL;
+  }
+  if (item->isTrigger) {
+    if (type == EnterNotify && !alreadyUp) {
+      GLUTmenu *submenu = __glutMenuList[item->value];
+
+      mapMenu(submenu,
+        item->menu->x + item->menu->pixwidth +
+        MENU_ARROW_GAP + MENU_ARROW_WIDTH +
+        MENU_GAP + MENU_BORDER,
+        item->menu->y + fontHeight * (num - 1) + MENU_GAP);
+      item->menu->cascade = submenu;
+      submenu->anchor = item;
+    }
+  }
+}
+
+/* Installs callback functions for use by glut_event.c  The point
+   of this is so that GLUT's menu code only gets linked into
+   GLUT binaries (assuming a static library) if the GLUT menu
+   API is used. */
+static void
+installMenuCallbacks(void)
+{
+  __glutMenuItemEnterOrLeave = menuItemEnterOrLeave;
+  __glutFinishMenu = finishMenu;
+  __glutPaintMenu = paintMenu;
+  __glutStartMenu = startMenu;
+  __glutGetMenuByNum = getMenuByNum;
+  __glutGetMenu = getMenu;
+  __glutGetMenuItem = getMenuItem;
+}
+
+int APIENTRY 
+glutCreateMenu(GLUTselectCB selectFunc)
+{
+  XSetWindowAttributes wa;
+  GLUTmenu *menu;
+  int menuid;
+
+  if (__glutMappedMenu) {
+    __glutMenuModificationError();
+  }
+  if (!__glutDisplay) {
+    __glutOpenXConnection(NULL);
+  }
+
+  installMenuCallbacks();
+
+  menuid = getUnusedMenuSlot();
+  menu = (GLUTmenu *) malloc(sizeof(GLUTmenu));
+  if (!menu) {
+    __glutFatalError("out of memory.");
+  }
+  menu->id = menuid;
+  menu->num = 0;
+  menu->submenus = 0;
+  menu->managed = False;
+  menu->searched = False;
+  menu->pixwidth = 0;
+  menu->select = selectFunc;
+  menu->list = NULL;
+  menu->cascade = NULL;
+  menu->highlighted = NULL;
+  menu->anchor = NULL;
+  menuSetup();
+  wa.override_redirect = True;
+  wa.background_pixel = menuGray;
+  wa.border_pixel = menuBlack;
+  wa.colormap = menuColormap;
+  wa.event_mask = StructureNotifyMask | ExposureMask |
+    ButtonPressMask | ButtonReleaseMask |
+    EnterWindowMask | LeaveWindowMask;
+  /* Save unders really only enabled if useSaveUnders is set to
+     CWSaveUnder, ie. using Mesa 3D.  See earlier comments. */
+  wa.save_under = True;
+  menu->win = XCreateWindow(__glutDisplay, __glutRoot,
+  /* Real position determined when mapped. */
+    0, 0,
+  /* Real size will be determined when menu is manged. */
+    1, 1,
+    MENU_BORDER, menuDepth, InputOutput, menuVisual,
+    CWOverrideRedirect | CWBackPixel | CWBorderPixel |
+    CWEventMask | CWColormap | useSaveUnders,
+    &wa);
+  menuGraphicsContextSetup(menu->win);
+  __glutMenuList[menuid] = menu;
+  __glutSetMenu(menu);
+  return menuid + 1;
+}
+
+/* CENTRY */
+int APIENTRY 
+glutGetMenu(void)
+{
+  if (__glutCurrentMenu) {
+    return __glutCurrentMenu->id + 1;
+  } else {
+    return 0;
+  }
+}
+
+void APIENTRY 
+glutSetMenu(int menuid)
+{
+  GLUTmenu *menu;
+
+  if (menuid < 1 || menuid > menuListSize) {
+    __glutWarning("glutSetMenu attempted on bogus menu.");
+    return;
+  }
+  menu = __glutMenuList[menuid - 1];
+  if (!menu) {
+    __glutWarning("glutSetMenu attempted on bogus menu.");
+    return;
+  }
+  __glutSetMenu(menu);
+}
+/* ENDCENTRY */
+
+void
+__glutSetMenuItem(GLUTmenuItem * item, const char *label,
+  int value, Bool isTrigger)
+{
+  GLUTmenu *menu;
+
+  menu = item->menu;
+  item->label = __glutStrdup(label);
+  if (!item->label) {
+    __glutFatalError("out of memory.");
+  }
+  item->isTrigger = isTrigger;
+  item->len = (int) strlen(label);
+  item->value = value;
+  item->pixwidth = XTextWidth(menuFont, label, item->len) + 4;
+  if (item->pixwidth > menu->pixwidth) {
+    menu->pixwidth = item->pixwidth;
+  }
+  menu->managed = False;
+}
+
+/* CENTRY */
+void APIENTRY 
+glutAddMenuEntry(const char *label, int value)
+{
+  XSetWindowAttributes wa;
+  GLUTmenuItem *entry;
+
+  if (__glutMappedMenu) {
+    __glutMenuModificationError();
+  }
+  entry = (GLUTmenuItem *) malloc(sizeof(GLUTmenuItem));
+  if (!entry) {
+    __glutFatalError("out of memory.");
+  }
+  entry->menu = __glutCurrentMenu;
+  __glutSetMenuItem(entry, label, value, False);
+  wa.event_mask = EnterWindowMask | LeaveWindowMask;
+  entry->win = XCreateWindow(__glutDisplay,
+    __glutCurrentMenu->win, MENU_GAP,
+    __glutCurrentMenu->num * fontHeight + MENU_GAP,  /* x & y */
+    entry->pixwidth, fontHeight,  /* width & height */
+    0, CopyFromParent, InputOnly, CopyFromParent,
+    CWEventMask, &wa);
+  XMapWindow(__glutDisplay, entry->win);
+  __glutCurrentMenu->num++;
+  entry->next = __glutCurrentMenu->list;
+  __glutCurrentMenu->list = entry;
+}
+
+void APIENTRY 
+glutAddSubMenu(const char *label, int menu)
+{
+  XSetWindowAttributes wa;
+  GLUTmenuItem *submenu;
+
+  if (__glutMappedMenu) {
+    __glutMenuModificationError();
+  }
+  submenu = (GLUTmenuItem *) malloc(sizeof(GLUTmenuItem));
+  if (!submenu) {
+    __glutFatalError("out of memory.");
+  }
+  __glutCurrentMenu->submenus++;
+  submenu->menu = __glutCurrentMenu;
+  __glutSetMenuItem(submenu, label, /* base 0 */ menu - 1, True);
+  wa.event_mask = EnterWindowMask | LeaveWindowMask;
+  submenu->win = XCreateWindow(__glutDisplay,
+    __glutCurrentMenu->win, MENU_GAP,
+    __glutCurrentMenu->num * fontHeight + MENU_GAP,  /* x & y */
+    submenu->pixwidth, fontHeight,  /* width & height */
+    0, CopyFromParent, InputOnly, CopyFromParent,
+    CWEventMask, &wa);
+  XMapWindow(__glutDisplay, submenu->win);
+  __glutCurrentMenu->num++;
+  submenu->next = __glutCurrentMenu->list;
+  __glutCurrentMenu->list = submenu;
+}
+
+void APIENTRY 
+glutAttachMenu(int button)
+{
+  if (__glutMappedMenu) {
+    __glutMenuModificationError();
+  }
+  installMenuCallbacks();
+  if (__glutCurrentWindow->menu[button] < 1) {
+    __glutCurrentWindow->buttonUses++;
+  }
+  __glutChangeWindowEventMask(
+    ButtonPressMask | ButtonReleaseMask, True);
+  __glutCurrentWindow->menu[button] = __glutCurrentMenu->id + 1;
+}
+/* ENDCENTRY */