diff -r 7cc35bc348cc src/DLD-FUNCTIONS/fltk_backend.cc
--- a/src/DLD-FUNCTIONS/fltk_backend.cc	Sun Jun 28 08:51:41 2009 +0100
+++ b/src/DLD-FUNCTIONS/fltk_backend.cc	Mon Jun 29 23:07:01 2009 +0200
@@ -442,63 +442,116 @@
 	pixel2status (px0, py0, Fl::event_x (), Fl::event_y ());
 	if (Fl::event_button () == 1)
 	  {
-	    canvas->zoom (true);
-	    Matrix zoom_box (1,4,0);
-	    zoom_box (0) = px0;
-	    zoom_box (1) = py0;
-	    zoom_box (2) =  Fl::event_x ();
-	    zoom_box (3) =  Fl::event_y ();
-	    canvas->set_zoom_box (zoom_box);
-	    canvas->redraw_overlay ();
+	    // XXX: These limits are hard-coded because I couldn't figure out
+            // XXX: how to get them from the axes
+            const double minx = 0, maxx = 10, miny = 0, maxy = 10;
+          
+            graphics_object ax = gh_manager::get_object (fp.get_currentaxes ());
+            if (ax && ax.isa ("axes"))
+              {
+                axes::properties& ap = dynamic_cast<axes::properties&> (ax.get_properties ());
+              
+                // Get current axes limits (FIXME: Handle 3D)
+                // FIXME: Do we need error checking here?
+                Matrix xlim = ap.get_xlim ().matrix_value ();
+                Matrix ylim = ap.get_ylim ().matrix_value ();
+              
+                double x0, y0, x1, y1;
+                pixel2pos (px0, py0, x0, y0);
+                pixel2pos (Fl::event_x (), Fl::event_y (), x1, y1);
+                px0 = Fl::event_x ();
+                py0 = Fl::event_y ();
+
+                double delta_x = x0 - x1;
+                if (delta_x > 0)
+                  delta_x = std::min (xlim (1) + delta_x, maxx) - xlim (1);
+                else
+                  delta_x = std::max (xlim (0) + delta_x, minx) - xlim (0);
+                xlim (0) = xlim (0) + delta_x;
+                xlim (1) = xlim (1) + delta_x;
+                
+                double delta_y = y0 - y1;
+                if (delta_y > 0)
+                  delta_y = std::min (ylim (1) + delta_y, maxy) - ylim (1);
+                else
+                  delta_y = std::max (ylim (0) + delta_y, miny) - ylim (0);
+                ylim (0) = ylim (0) + delta_y;
+                ylim (1) = ylim (1) + delta_y;
+                
+                ap.zoom (xlim, ylim);
+                mark_modified ();
+              }
 	    return 1;
 	  }
 	break;
 
+      case FL_MOUSEWHEEL:
+        {
+          // Parameter controlling how fast we zoom. FIXME: Should this be user tweakable?
+          const double zoom_speed = 1.0 / 10.0;
+
+          // XXX: These limits are hard-coded because I couldn't figure out
+          // XXX: how to get them from the axes
+          const double minx = 0, maxx = 10, miny = 0, maxy = 10;
+          
+          const double max_delta_x = maxx - minx;
+          const double max_delta_y = maxy - miny;
+          
+          graphics_object ax = gh_manager::get_object (fp.get_currentaxes ());
+          if (ax && ax.isa ("axes"))
+            {
+              axes::properties& ap = dynamic_cast<axes::properties&> (ax.get_properties ());
+              
+              // Get current axes limits (FIXME: Handle 3D)
+              // FIXME: Do we need error checking here?
+              Matrix xlim = ap.get_xlim ().matrix_value ();
+              Matrix ylim = ap.get_ylim ().matrix_value ();
+              
+              const double delta_x = xlim (1) - xlim (0);
+              const double delta_y = ylim (1) - ylim (0);
+              
+              double x1, y1;
+              pixel2pos (Fl::event_x (), Fl::event_y (), x1, y1);
+              
+              const double direction = (Fl::event_dy () > 0) ? 1.0 : -1.0;
+              const double new_delta_x =
+                std::min (delta_x + direction * 2.0 * zoom_speed, max_delta_x);
+              const double new_delta_y =
+                std::min (delta_y + direction * 2.0 * zoom_speed, max_delta_y);
+              
+              const double center_x = xlim (0) + delta_x / 2.0;
+              const double center_y = ylim (0) + delta_y / 2.0;
+              double new_center_x = (x1 > center_x) 
+                                  ? center_x + zoom_speed : center_x - zoom_speed;
+              double new_center_y = (y1 > center_y) 
+                                  ? center_y + zoom_speed : center_y - zoom_speed;
+
+              if (new_center_x + new_delta_x / 2.0 > maxx)
+                new_center_x = maxx - new_delta_x / 2.0;
+              if (new_center_x - new_delta_x / 2.0 < minx)
+                new_center_x = minx + new_delta_x / 2.0;
+
+              if (new_center_y + new_delta_y / 2.0 > maxy)
+                new_center_y = maxy - new_delta_y / 2.0;
+              if (new_center_y - new_delta_y / 2.0 < minx)
+                new_center_y = miny + new_delta_y / 2.0;
+              
+              xlim (0) = new_center_x - new_delta_x / 2.0;
+              xlim (1) = new_center_x + new_delta_x / 2.0;
+              ylim (0) = new_center_y - new_delta_y / 2.0;
+              ylim (1) = new_center_y + new_delta_y / 2.0;
+                
+              ap.zoom (xlim, ylim);
+              mark_modified ();
+            }
+	}
+      return 1;
+
       case FL_RELEASE:
 	if (Fl::event_button () == 1)
 	  {
-	    // end of drag -- zoom
-	    if (canvas->zoom ())
-	      {
-		canvas->zoom (false);
-		double x0,y0,x1,y1;
-		graphics_object ax =
-		  gh_manager::get_object (fp.get_currentaxes ());
-		if (ax && ax.isa ("axes"))
-		  {
-		    axes::properties& ap =
-		      dynamic_cast<axes::properties&> (ax.get_properties ());
-		    pixel2pos (px0, py0, x0, y0);
-		    pixel2pos (Fl::event_x (), Fl::event_y (), x1, y1);
-		    Matrix xl (1,2,0);
-		    Matrix yl (1,2,0);
-		    if (x0 < x1)
-		      {
-			xl(0) = x0;
-			xl(1) = x1;
-		      }
-		    else
-		      {
-			xl(0) = x1;
-			xl(1) = x0;
-		      }
-
-		    if (y0 < y1)
-		      {
-			yl(0) = y0;
-			yl(1) = y1;
-		      }
-		    else
-		      {
-			yl(0) = y1;
-			yl(1) = y0;
-		      }
-		    ap.zoom (xl, yl);
-		    mark_modified ();
-		  }
-	      }
 	    // one click -- select axes
-	    else if ( Fl::event_clicks () == 0)
+	    if ( Fl::event_clicks () == 0)
 	      {
 		std::cout << "ca="<< h0.value ()<<"\n";
 		if (h0.ok ())