This patch fixes the following problems with BLT 2.4z

  1) BLT won't load into more than one interpreter.

  2) Hiding an element 
     
        .graph element configure "e0" -hide yes

    also hides the legend entry.

Apply this patch from the top of the blt2.4z source tree (i.e.
the directory that contains "blt2.4z").

  --gah

diff -cr blt2.4z-old/src/bltGrAxis.c blt2.4z/src/bltGrAxis.c
*** blt2.4z-old/src/bltGrAxis.c	2002-09-18 17:30:51.000000000 -0500
--- blt2.4z/src/bltGrAxis.c	2002-12-02 22:39:26.000000000 -0600
***************
*** 1424,1482 ****
      double majorStep, minorStep;
      int nMajor, nMinor;
  
!     min = (min != 0.0) ? log10(FABS(min)) : 0.0;
!     max = (max != 0.0) ? log10(FABS(max)) : 1.0;
! 
!     tickMin = floor(min);
!     tickMax = ceil(max);
!     range = tickMax - tickMin;
! 
!     if (range > 10) {
! 	/* There are too many decades to display a major tick at every
! 	 * decade.  Instead, treat the axis as a linear scale.  */
! 	range = NiceNum(range, 0);
! 	majorStep = NiceNum(range / DEF_NUM_TICKS, 1);
! 	tickMin = UFLOOR(tickMin, majorStep);
! 	tickMax = UCEIL(tickMax, majorStep);
! 	nMajor = (int)((tickMax - tickMin) / majorStep) + 1;
! 	minorStep = EXP10(floor(log10(majorStep)));
! 	if (minorStep == majorStep) {
! 	    nMinor = 4, minorStep = 0.2;
  	} else {
! 	    nMinor = Round(majorStep / minorStep) - 1;
! 	}
!     } else {
! 	if (tickMin == tickMax) {
! 	    tickMax++;
! 	}
! 	majorStep = 1.0;
! 	nMajor = (int)(tickMax - tickMin + 1); /* FIXME: Check this. */
! 
! 	minorStep = 0.0;	/* This is a special hack to pass
  				 * information to the GenerateTicks
  				 * routine. An interval of 0.0 tells
  				 *	1) this is a minor sweep and 
  				 *	2) the axis is log scale.  
  				 */
! 	nMinor = 10;
!     }
!     if ((axisPtr->looseMin == TICK_RANGE_TIGHT) ||
! 	((axisPtr->looseMin == TICK_RANGE_LOOSE) && 
! 	 (DEFINED(axisPtr->reqMin)))) {
! 	tickMin = min;
! 	nMajor++;
!     }
!     if ((axisPtr->looseMax == TICK_RANGE_TIGHT) ||
! 	((axisPtr->looseMax == TICK_RANGE_LOOSE) &&
! 	 (DEFINED(axisPtr->reqMax)))) {
! 	tickMax = max;
      }
      axisPtr->majorSweep.step = majorStep;
      axisPtr->majorSweep.initial = floor(tickMin);
      axisPtr->majorSweep.nSteps = nMajor;
      axisPtr->minorSweep.initial = axisPtr->minorSweep.step = minorStep;
      axisPtr->minorSweep.nSteps = nMinor;
- 
      SetAxisRange(&axisPtr->axisRange, tickMin, tickMax);
  }
  
--- 1424,1485 ----
      double majorStep, minorStep;
      int nMajor, nMinor;
  
!     nMajor = nMinor = 0;
!     majorStep = minorStep = 0.0;
!     if (min < max) {
! 	min = (min != 0.0) ? log10(FABS(min)) : 0.0;
! 	max = (max != 0.0) ? log10(FABS(max)) : 1.0;
! 	
! 	tickMin = floor(min);
! 	tickMax = ceil(max);
! 	range = tickMax - tickMin;
! 	
! 	if (range > 10) {
! 	    /* There are too many decades to display a major tick at every
! 	     * decade.  Instead, treat the axis as a linear scale.  */
! 	    range = NiceNum(range, 0);
! 	    majorStep = NiceNum(range / DEF_NUM_TICKS, 1);
! 	    tickMin = UFLOOR(tickMin, majorStep);
! 	    tickMax = UCEIL(tickMax, majorStep);
! 	    nMajor = (int)((tickMax - tickMin) / majorStep) + 1;
! 	    minorStep = EXP10(floor(log10(majorStep)));
! 	    if (minorStep == majorStep) {
! 		nMinor = 4, minorStep = 0.2;
! 	    } else {
! 		nMinor = Round(majorStep / minorStep) - 1;
! 	    }
  	} else {
! 	    if (tickMin == tickMax) {
! 		tickMax++;
! 	    }
! 	    majorStep = 1.0;
! 	    nMajor = (int)(tickMax - tickMin + 1); /* FIXME: Check this. */
! 	    
! 	    minorStep = 0.0;	/* This is a special hack to pass
  				 * information to the GenerateTicks
  				 * routine. An interval of 0.0 tells
  				 *	1) this is a minor sweep and 
  				 *	2) the axis is log scale.  
  				 */
! 	    nMinor = 10;
! 	}
! 	if ((axisPtr->looseMin == TICK_RANGE_TIGHT) ||
! 	    ((axisPtr->looseMin == TICK_RANGE_LOOSE) && 
! 	     (DEFINED(axisPtr->reqMin)))) {
! 	    tickMin = min;
! 	    nMajor++;
! 	}
! 	if ((axisPtr->looseMax == TICK_RANGE_TIGHT) ||
! 	    ((axisPtr->looseMax == TICK_RANGE_LOOSE) &&
! 	     (DEFINED(axisPtr->reqMax)))) {
! 	    tickMax = max;
! 	}
      }
      axisPtr->majorSweep.step = majorStep;
      axisPtr->majorSweep.initial = floor(tickMin);
      axisPtr->majorSweep.nSteps = nMajor;
      axisPtr->minorSweep.initial = axisPtr->minorSweep.step = minorStep;
      axisPtr->minorSweep.nSteps = nMinor;
      SetAxisRange(&axisPtr->axisRange, tickMin, tickMax);
  }
  
***************
*** 1551,1581 ****
      double axisMin, axisMax;
      int nTicks;
  
!     range = max - min;
! 
!     /* Calculate the major tick stepping. */
!     if (axisPtr->reqStep > 0.0) {
! 	/* An interval was designated by the user.  Keep scaling it
! 	 * until it fits comfortably within the current range of the
! 	 * axis.  */
! 	step = axisPtr->reqStep;
! 	while ((2 * step) >= range) {
! 	    step *= 0.5;
  	}
!     } else {
! 	range = NiceNum(range, 0);
! 	step = NiceNum(range / DEF_NUM_TICKS, 1);
      }
- 
-     /* Find the outer tick values. Add 0.0 to prevent getting -0.0. */
-     axisMin = tickMin = floor(min / step) * step + 0.0;
-     axisMax = tickMax = ceil(max / step) * step + 0.0;
- 
-     nTicks = Round((tickMax - tickMin) / step) + 1;
      axisPtr->majorSweep.step = step;
      axisPtr->majorSweep.initial = tickMin;
      axisPtr->majorSweep.nSteps = nTicks;
! 
      /*
       * The limits of the axis are either the range of the data
       * ("tight") or at the next outer tick interval ("loose").  The
--- 1554,1588 ----
      double axisMin, axisMax;
      int nTicks;
  
!     nTicks = 0;
!     tickMin = tickMax = 0.0;
!     if (min < max) {
! 	range = max - min;
! 	
! 	/* Calculate the major tick stepping. */
! 	if (axisPtr->reqStep > 0.0) {
! 	    /* An interval was designated by the user.  Keep scaling it
! 	     * until it fits comfortably within the current range of the
! 	     * axis.  */
! 	    step = axisPtr->reqStep;
! 	    while ((2 * step) >= range) {
! 		step *= 0.5;
! 	    }
! 	} else {
! 	    range = NiceNum(range, 0);
! 	    step = NiceNum(range / DEF_NUM_TICKS, 1);
  	}
! 	
! 	/* Find the outer tick values. Add 0.0 to prevent getting -0.0. */
! 	axisMin = tickMin = floor(min / step) * step + 0.0;
! 	axisMax = tickMax = ceil(max / step) * step + 0.0;
! 	
! 	nTicks = Round((tickMax - tickMin) / step) + 1;
      }
      axisPtr->majorSweep.step = step;
      axisPtr->majorSweep.initial = tickMin;
      axisPtr->majorSweep.nSteps = nTicks;
!     
      /*
       * The limits of the axis are either the range of the data
       * ("tight") or at the next outer tick interval ("loose").  The
***************
*** 1596,1604 ****
  	axisMax = max;
      }
      SetAxisRange(&axisPtr->axisRange, axisMin, axisMax);
! 
      /* Now calculate the minor tick step and number. */
! 
      if ((axisPtr->reqNumMinorTicks > 0) && 
  	((axisPtr->flags & AXIS_CONFIG_MAJOR) == 0)) {
  	nTicks = axisPtr->reqNumMinorTicks - 1;
--- 1603,1611 ----
  	axisMax = max;
      }
      SetAxisRange(&axisPtr->axisRange, axisMin, axisMax);
!     
      /* Now calculate the minor tick step and number. */
!     
      if ((axisPtr->reqNumMinorTicks > 0) && 
  	((axisPtr->flags & AXIS_CONFIG_MAJOR) == 0)) {
  	nTicks = axisPtr->reqNumMinorTicks - 1;
***************
*** 1614,1620 ****
      axisPtr->minorSweep.nSteps = nTicks;
  }
  
- 
  static void
  SweepTicks(axisPtr)
      Axis *axisPtr;
--- 1621,1626 ----
***************
*** 1684,1692 ****
      for (linkPtr = Blt_ChainFirstLink(graphPtr->elements.displayList);
  	linkPtr != NULL; linkPtr = Blt_ChainNextLink(linkPtr)) {
  	elemPtr = Blt_ChainGetValue(linkPtr);
! 	(*elemPtr->procsPtr->extentsProc) (elemPtr, &exts);
! 	GetDataLimits(elemPtr->axes.x, exts.left, exts.right);
! 	GetDataLimits(elemPtr->axes.y, exts.top, exts.bottom);
      }
      /*
       * Step 3:  Now that we know the range of data values for each axis,
--- 1690,1700 ----
      for (linkPtr = Blt_ChainFirstLink(graphPtr->elements.displayList);
  	linkPtr != NULL; linkPtr = Blt_ChainNextLink(linkPtr)) {
  	elemPtr = Blt_ChainGetValue(linkPtr);
! 	if (!elemPtr->hidden) {
! 	    (*elemPtr->procsPtr->extentsProc) (elemPtr, &exts);
! 	    GetDataLimits(elemPtr->axes.x, exts.left, exts.right);
! 	    GetDataLimits(elemPtr->axes.y, exts.top, exts.bottom);
! 	}
      }
      /*
       * Step 3:  Now that we know the range of data values for each axis,
diff -cr blt2.4z-old/src/bltGrElem.c blt2.4z/src/bltGrElem.c
*** blt2.4z-old/src/bltGrElem.c	2002-09-18 17:30:51.000000000 -0500
--- blt2.4z/src/bltGrElem.c	2002-12-02 22:42:31.000000000 -0600
***************
*** 1215,1223 ****
  {
      int nNames;			/* Number of names found in Tcl name list */
      char **nameArr;		/* Broken out array of element names */
-     Blt_HashSearch cursor;
      register int i;
-     register Blt_HashEntry *hPtr;
      Element *elemPtr;		/* Element information record */
  
      if (Tcl_SplitList(graphPtr->interp, newList, &nNames, &nameArr) != TCL_OK) {
--- 1215,1221 ----
***************
*** 1227,1243 ****
      }
      /* Clear the display list and mark all elements as hidden.  */
      Blt_ChainReset(graphPtr->elements.displayList);
-     for (hPtr = Blt_FirstHashEntry(&graphPtr->elements.table, &cursor);
- 	hPtr != NULL; hPtr = Blt_NextHashEntry(&cursor)) {
- 	elemPtr = (Element *)Blt_GetHashValue(hPtr);
- 	elemPtr->hidden = TRUE;
-     }
  
      /* Rebuild the display list, checking that each name it exists
       * (currently ignoring invalid element names).  */
      for (i = 0; i < nNames; i++) {
  	if (NameToElement(graphPtr, nameArr[i], &elemPtr) == TCL_OK) {
- 	    elemPtr->hidden = FALSE;
  	    Blt_ChainAppend(graphPtr->elements.displayList, elemPtr);
  	}
      }
--- 1225,1235 ----
***************
*** 1399,1406 ****
  	    /* Comment the PostScript to indicate the start of the element */
  	    Blt_FormatToPostScript(psToken, "\n%% Element \"%s\"\n\n", 
  		elemPtr->name);
! 	    (*elemPtr->procsPtr->printNormalProc) (graphPtr, psToken, 
! 		elemPtr);
  	}
      }
  }
--- 1391,1397 ----
  	    /* Comment the PostScript to indicate the start of the element */
  	    Blt_FormatToPostScript(psToken, "\n%% Element \"%s\"\n\n", 
  		elemPtr->name);
! 	    (*elemPtr->procsPtr->printNormalProc) (graphPtr, psToken, elemPtr);
  	}
      }
  }
***************
*** 1426,1433 ****
  	if ((!elemPtr->hidden) && (elemPtr->flags & ELEM_ACTIVE)) {
  	    Blt_FormatToPostScript(psToken, "\n%% Active Element \"%s\"\n\n",
  		elemPtr->name);
! 	    (*elemPtr->procsPtr->printActiveProc) (graphPtr, psToken, 
! 						   elemPtr);
  	}
      }
  }
--- 1417,1423 ----
  	if ((!elemPtr->hidden) && (elemPtr->flags & ELEM_ACTIVE)) {
  	    Blt_FormatToPostScript(psToken, "\n%% Active Element \"%s\"\n\n",
  		elemPtr->name);
! 	    (*elemPtr->procsPtr->printActiveProc) (graphPtr, psToken, elemPtr);
  	}
      }
  }
***************
*** 1671,1676 ****
--- 1661,1667 ----
      ClosestSearch search;
      int i, x, y;
      int flags = TCL_LEAVE_ERR_MSG;
+     int found;
  
      if (graphPtr->flags & RESET_AXES) {
  	Blt_ResetAxes(graphPtr);
***************
*** 1715,1727 ****
      search.dist = (double)(search.halo + 1);
  
      if (i < argc) {
  	for ( /* empty */ ; i < argc; i++) {
  	    if (NameToElement(graphPtr, argv[i], &elemPtr) != TCL_OK) {
  		return TCL_ERROR;	/* Can't find named element */
  	    }
! 	    if (elemPtr->hidden) {
  		Tcl_AppendResult(interp, "element \"", argv[i], "\" is hidden",
! 		    (char *)NULL);
  		return TCL_ERROR;	/* Element isn't visible */
  	    }
  	    /* Check if the X or Y vectors have notifications pending */
--- 1706,1728 ----
      search.dist = (double)(search.halo + 1);
  
      if (i < argc) {
+ 	Blt_ChainLink *linkPtr;
+ 
  	for ( /* empty */ ; i < argc; i++) {
  	    if (NameToElement(graphPtr, argv[i], &elemPtr) != TCL_OK) {
  		return TCL_ERROR;	/* Can't find named element */
  	    }
! 	    found = FALSE;
! 	    for (linkPtr = Blt_ChainFirstLink(graphPtr->elements.displayList);
! 		 linkPtr == NULL; linkPtr = Blt_ChainNextLink(linkPtr)) {
! 		if (elemPtr == Blt_ChainGetValue(linkPtr)) {
! 		    found = TRUE;
! 		    break;
! 		}
! 	    }
! 	    if ((!found) || (elemPtr->hidden)) {
  		Tcl_AppendResult(interp, "element \"", argv[i], "\" is hidden",
! 			(char *)NULL);
  		return TCL_ERROR;	/* Element isn't visible */
  	    }
  	    /* Check if the X or Y vectors have notifications pending */
***************
*** 1744,1759 ****
  	for (linkPtr = Blt_ChainLastLink(graphPtr->elements.displayList);
  	    linkPtr != NULL; linkPtr = Blt_ChainPrevLink(linkPtr)) {
  	    elemPtr = Blt_ChainGetValue(linkPtr);
- 
  	    /* Check if the X or Y vectors have notifications pending */
! 	    if ((elemPtr->flags & MAP_ITEM) ||
  		(Blt_VectorNotifyPending(elemPtr->x.clientId)) ||
  		(Blt_VectorNotifyPending(elemPtr->y.clientId))) {
  		continue;
  	    }
! 	    if (!elemPtr->hidden) {
! 		(*elemPtr->procsPtr->closestProc) (graphPtr, elemPtr, &search);
! 	    }
  	}
  
      }
--- 1745,1758 ----
  	for (linkPtr = Blt_ChainLastLink(graphPtr->elements.displayList);
  	    linkPtr != NULL; linkPtr = Blt_ChainPrevLink(linkPtr)) {
  	    elemPtr = Blt_ChainGetValue(linkPtr);
  	    /* Check if the X or Y vectors have notifications pending */
! 	    if ((elemPtr->hidden) || 
! 		(elemPtr->flags & MAP_ITEM) ||
  		(Blt_VectorNotifyPending(elemPtr->x.clientId)) ||
  		(Blt_VectorNotifyPending(elemPtr->y.clientId))) {
  		continue;
  	    }
! 	    (*elemPtr->procsPtr->closestProc)(graphPtr, elemPtr, &search);
  	}
  
      }
***************
*** 1859,1888 ****
  	    return TCL_ERROR;	/* Failed to configure element */
  	}
  	if (Blt_ConfigModified(elemPtr->specsPtr, "-hide", (char *)NULL)) {
- 	    Blt_ChainLink *linkPtr;
- 
- 	    for (linkPtr = Blt_ChainFirstLink(graphPtr->elements.displayList);
- 		linkPtr != NULL; linkPtr = Blt_ChainNextLink(linkPtr)) {
- 		if (elemPtr == Blt_ChainGetValue(linkPtr)) {
- 		    break;
- 		}
- 	    }
- 	    if ((elemPtr->hidden) != (linkPtr == NULL)) {
- 
- 		/* The element's "hidden" variable is out of sync with
- 		 * the display list. [That's what you get for having
- 		 * two ways to do the same thing.]  This affects what
- 		 * elements are considered for axis ranges and
- 		 * displayed in the legend. Update the display list by
- 		 * either by adding or removing the element.  */
- 
- 		if (linkPtr == NULL) {
- 		    Blt_ChainPrepend(graphPtr->elements.displayList, elemPtr);
- 		} else {
- 		    Blt_ChainDeleteLink(graphPtr->elements.displayList, 
- 					linkPtr);
- 		}
- 	    }
  	    graphPtr->flags |= RESET_AXES;
  	    elemPtr->flags |= MAP_ITEM;
  	}
--- 1858,1863 ----
diff -cr blt2.4z-old/src/bltInit.c blt2.4z/src/bltInit.c
*** blt2.4z-old/src/bltInit.c	2002-09-10 00:12:33.000000000 -0500
--- blt2.4z/src/bltInit.c	2002-12-02 22:25:33.000000000 -0600
***************
*** 38,54 ****
  #endif
  #endif
  
  double bltNaN;
  #if (TCL_MAJOR_VERSION > 7)
  Tcl_Obj *bltEmptyStringObjPtr;
  #endif
  
  static Tcl_MathProc MinMathProc, MaxMathProc;
- static int tclLoaded = FALSE;
- #ifndef TCL_ONLY
- static int tkLoaded = FALSE;
- #endif
- 
  static char libPath[1024] =
  {
      BLT_LIBRARY
--- 38,53 ----
  #endif
  #endif
  
+ #define BLT_THREAD_KEY		"BLT Initialized"
+ #define BLT_TCL_CMDS		(1<<0)
+ #define BLT_TK_CMDS		(1<<1)
+ 
  double bltNaN;
  #if (TCL_MAJOR_VERSION > 7)
  Tcl_Obj *bltEmptyStringObjPtr;
  #endif
  
  static Tcl_MathProc MinMathProc, MaxMathProc;
  static char libPath[1024] =
  {
      BLT_LIBRARY
***************
*** 404,410 ****
  Blt_Init(interp)
      Tcl_Interp *interp;		/* Interpreter to add extra commands */
  {
!     if (!tclLoaded) {
  	register Tcl_AppInitProc **p;
  	Tcl_Namespace *nsPtr;
  	Tcl_ValueType args[2];
--- 403,412 ----
  Blt_Init(interp)
      Tcl_Interp *interp;		/* Interpreter to add extra commands */
  {
!     int flags;
! 
!     flags = (int)Tcl_GetAssocData(interp, BLT_THREAD_KEY, NULL);
!     if ((flags & BLT_TCL_CMDS) == 0) {
  	register Tcl_AppInitProc **p;
  	Tcl_Namespace *nsPtr;
  	Tcl_ValueType args[2];
***************
*** 451,460 ****
  	if (Tcl_PkgProvide(interp, "BLT", BLT_VERSION) != TCL_OK) {
  	    return TCL_ERROR;
  	}
! 	tclLoaded = TRUE;
      }
  #ifndef TCL_ONLY
!     if (!tkLoaded) {
  	register Tcl_AppInitProc **p;
  	Tcl_Namespace *nsPtr;
  
--- 453,463 ----
  	if (Tcl_PkgProvide(interp, "BLT", BLT_VERSION) != TCL_OK) {
  	    return TCL_ERROR;
  	}
! 	Tcl_SetAssocData(interp, BLT_THREAD_KEY, NULL, 
! 		(ClientData)(flags | BLT_TCL_CMDS));
      }
  #ifndef TCL_ONLY
!     if ((flags & BLT_TK_CMDS) == 0) {
  	register Tcl_AppInitProc **p;
  	Tcl_Namespace *nsPtr;
  
***************
*** 486,492 ****
  	    }
  	}
  	Blt_InitEpsCanvasItem(interp);
! 	tkLoaded = TRUE;
      }
  #endif
      return TCL_OK;
--- 489,496 ----
  	    }
  	}
  	Blt_InitEpsCanvasItem(interp);
! 	Tcl_SetAssocData(interp, BLT_THREAD_KEY, NULL, 
! 		(ClientData)(flags | BLT_TK_CMDS));
      }
  #endif
      return TCL_OK;
***************
*** 499,505 ****
  Blt_Init(interp)
      Tcl_Interp *interp;		/* Interpreter to add extra commands */
  {
!     if (!tclLoaded) {
  	register Tcl_AppInitProc **p;
  	Tcl_ValueType args[2];
  
--- 503,512 ----
  Blt_Init(interp)
      Tcl_Interp *interp;		/* Interpreter to add extra commands */
  {
!     int flags;
! 
!     flags = (int)Tcl_GetAssocData(interp, BLT_THREAD_KEY, NULL);
!     if ((flags & BLT_TCL_CMDS) == 0) {
  	register Tcl_AppInitProc **p;
  	Tcl_ValueType args[2];
  
***************
*** 537,546 ****
  	if (Tcl_PkgProvide(interp, "BLT", BLT_VERSION) != TCL_OK) {
  	    return TCL_ERROR;
  	}
! 	tclLoaded = TRUE;
      }
  #ifndef TCL_ONLY
!     if (!tkLoaded) {
  	register Tcl_AppInitProc **p;
  
  #if (TCL_VERSION_NUMBER >= _VERSION(8,1,0)) 
--- 544,554 ----
  	if (Tcl_PkgProvide(interp, "BLT", BLT_VERSION) != TCL_OK) {
  	    return TCL_ERROR;
  	}
! 	Tcl_SetAssocData(interp, BLT_THREAD_KEY, NULL, 
! 		(ClientData)(flags | BLT_TCL_CMDS));
      }
  #ifndef TCL_ONLY
!     if ((flags & BLT_TK_CMDS) == 0) {
  	register Tcl_AppInitProc **p;
  
  #if (TCL_VERSION_NUMBER >= _VERSION(8,1,0)) 
***************
*** 560,566 ****
  	    }
  	}
  	Blt_InitEpsCanvasItem(interp);
! 	tkLoaded = TRUE;
      }
  #endif
      return TCL_OK;
--- 568,575 ----
  	    }
  	}
  	Blt_InitEpsCanvasItem(interp);
! 	Tcl_SetAssocData(interp, BLT_THREAD_KEY, NULL, 
! 		(ClientData)(flags | BLT_TK_CMDS));
      }
  #endif
      return TCL_OK;