diff --git a/ChangeLog b/ChangeLog
index 15fbc451f1..d720269e05 100644
--- a/ChangeLog
+++ b/ChangeLog
@@ -1,3 +1,13 @@
+2004-01-11  Pedro Gimeno  <pggimeno@wanadoo.es>
+
+	* app/core/gimpdrawable-preview.c (gimp_drawable_preview_scale):
+	Apply threshold to alpha in the same way as it is applied to the
+	image in indexed mode. Fixes bug #115793, at least until the
+	alpha thresholds in indexed images are removed.
+
+	* plug-ins/FractalExplorer/Display.c: Fix zoom undo handling
+	issues. Closes bug #82478.
+
 2004-01-11  Dave Neary  <bolsh@gimp.org>
 
 	* etc/templaterc: Remove unusual "1200x900" template.
diff --git a/app/core/gimpdrawable-preview.c b/app/core/gimpdrawable-preview.c
index 911765bba4..711bcd0129 100644
--- a/app/core/gimpdrawable-preview.c
+++ b/app/core/gimpdrawable-preview.c
@@ -312,8 +312,10 @@ gimp_drawable_preview_scale (GimpImageBaseType  type,
 	      r[GREEN_PIX] += cmap[index++] * tot_frac;
 	      r[BLUE_PIX]  += cmap[index++] * tot_frac;
 
-	      if (bytes == 4)
-		r[ALPHA_PIX] += s[ALPHA_I_PIX] * tot_frac;
+              if (bytes == 4)
+                r[ALPHA_PIX] += ((s[ALPHA_I_PIX] & 0x80 ?
+                                  OPAQUE_OPACITY : TRANSPARENT_OPACITY)
+                                 * tot_frac);
 	    }
 	  else
 	    {
diff --git a/plug-ins/FractalExplorer/Dialogs.c b/plug-ins/FractalExplorer/Dialogs.c
index e2f1662b79..d180f70906 100644
--- a/plug-ins/FractalExplorer/Dialogs.c
+++ b/plug-ins/FractalExplorer/Dialogs.c
@@ -22,6 +22,7 @@
 
 
 #define RESPONSE_ABOUT 1
+#define ZOOM_UNDO_SIZE 100
 
 
 static gdouble          *gradient_samples = NULL;
@@ -32,9 +33,9 @@ static DialogElements   *elements = NULL;
 static GtkWidget        *cmap_preview;
 static GtkWidget        *maindlg;
 
-static explorer_vals_t  zooms[100];
-static gint             zoomindex = 1;
-static gint             zoommax = 1;
+static explorer_vals_t  zooms[ZOOM_UNDO_SIZE];
+static gint             zoomindex = 0;
+static gint             zoommax = 0;
 
 static gint              oldxpos = -1;
 static gint              oldypos = -1;
@@ -143,7 +144,7 @@ static void
 dialog_undo_zoom_callback (GtkWidget *widget,
                            gpointer   data)
 {
-  if (zoomindex > 1)
+  if (zoomindex > 0)
     {
       zooms[zoomindex] = wvals;
       zoomindex--;
@@ -175,11 +176,12 @@ dialog_step_in_callback (GtkWidget *widget,
   double xdifferenz;
   double ydifferenz;
 
-  if (zoomindex < zoommax)
+  if (zoomindex < ZOOM_UNDO_SIZE - 1)
     {
       zooms[zoomindex]=wvals;
       zoomindex++;
     }
+  zoommax = zoomindex;
 
   xdifferenz =  wvals.xmax - wvals.xmin;
   ydifferenz =  wvals.ymax - wvals.ymin;
@@ -201,11 +203,12 @@ dialog_step_out_callback (GtkWidget *widget,
   gdouble xdifferenz;
   gdouble ydifferenz;
 
-  if (zoomindex < zoommax)
+  if (zoomindex < ZOOM_UNDO_SIZE - 1)
     {
       zooms[zoomindex]=wvals;
       zoomindex++;
     }
+  zoommax = zoomindex;
 
   xdifferenz =  wvals.xmax - wvals.xmin;
   ydifferenz =  wvals.ymax - wvals.ymin;
@@ -459,10 +462,11 @@ preview_button_release_event (GtkWidget      *widget,
           l_ymax = (wvals.ymin +
                     (wvals.ymax - wvals.ymin) * (y_release / preview_height));
 
-          zooms[zoomindex] = wvals;
-          zoomindex++;
-          if (zoomindex > 99)
-            zoomindex = 99;
+          if (zoomindex < ZOOM_UNDO_SIZE - 1)
+            {
+              zooms[zoomindex] = wvals;
+              zoomindex++;
+            }
           zoommax = zoomindex;
           wvals.xmin = l_xmin;
           wvals.xmax = l_xmax;