diff --git a/src/callback.c b/src/callback.c
index 5935cf06..809df75e 100644
--- a/src/callback.c
+++ b/src/callback.c
@@ -2196,6 +2196,7 @@ static int handle_mouse_wheel(int event, int mx, int my, KeySym key, int button,
       waves_callback(event, mx, my, key, button, aux, state);
       return 1;
     }
+     /* zoom out */
      view_unzoom(CADZOOMSTEP);
      return 0;
    }
@@ -2204,6 +2205,7 @@ static int handle_mouse_wheel(int event, int mx, int my, KeySym key, int button,
       waves_callback(event, mx, my, key, button, aux, state);
       return 1;
     }
+     /* zoom in */
      view_zoom(CADZOOMSTEP);
      return 0;
    }
@@ -2213,6 +2215,7 @@ static int handle_mouse_wheel(int event, int mx, int my, KeySym key, int button,
         waves_callback(event, mx, my, key, button, aux, state);
         return 1;
       }
+      /* pan to the right; move schematic to left */
       xctx->xorigin+=-CADMOVESTEP*xctx->zoom/2.;
       draw();
       redraw_w_a_l_r_p_z_rubbers(1);
@@ -2222,16 +2225,20 @@ static int handle_mouse_wheel(int event, int mx, int my, KeySym key, int button,
         waves_callback(event, mx, my, key, button, aux, state);
         return 1;
       }
+
+      /* pan to the left; move schematic to right */
       xctx->xorigin-=-CADMOVESTEP*xctx->zoom/2.;
       draw();
       redraw_w_a_l_r_p_z_rubbers(1);
      }
      else if(button==Button4 && (state & ControlMask) && !(state & Button2Mask)) {
+      /* pan down; move schematic up */
       xctx->yorigin+=-CADMOVESTEP*xctx->zoom/2.;
       draw();
       redraw_w_a_l_r_p_z_rubbers(1);
      }
      else if(button==Button5 && (state & ControlMask) && !(state & Button2Mask)) {
+      /* pan up; move schematic down */
       xctx->yorigin-=-CADMOVESTEP*xctx->zoom/2.;
       draw();
       redraw_w_a_l_r_p_z_rubbers(1);
diff --git a/src/xschem.tcl b/src/xschem.tcl
index 1bdef451..1cbf6e1c 100644
--- a/src/xschem.tcl
+++ b/src/xschem.tcl
@@ -9950,7 +9950,7 @@ proc show_bindkeys {} {
 }
 
 proc set_bindings {topwin} {
-global env has_x OS autofocus_mainwindow
+global env has_x OS autofocus_mainwindow replace_key
   ###
   ### Tk event handling
   ###
@@ -9978,14 +9978,74 @@ global env has_x OS autofocus_mainwindow
     bind $topwin <Expose> "if {{%W} eq {$topwin}} {xschem callback %W %T %x %y 0 %w %h %s}"
 
     # transform mousewheel events into button4/5 events
-    if {[info tclversion] > 8.7} {
-      bind $topwin <MouseWheel> {
-        if {%D > 0} {
-          xschem callback %W 4 %x %y 0 4 0 %s
+    if {[info tclversion] >= 8.7} {
+      set zoom_state 0
+      set vert_pan_state 4
+      set horiz_pan_state 1
+      # transform mouse wheel modifier key remapping into MouseWheel equivalents
+      if {[info exist replace_key(Button-4)]} {
+        if {[regexp {Control} $replace_key(Button-4)]} {
+          set zoom_state 4
+        } elseif {[regexp {Shift} $replace_key(Button-4)]} {
+          set zoom_state 1
         } else {
-          xschem callback %W 4 %x %y 0 5 0 %s
+          set zoom_state 0
         }
       }
+  
+      if {[info exist replace_key(Shift-Button-4)]} {
+        if {[regexp {Control} $replace_key(Shift-Button-4)]} {
+          set horiz_pan_state 4
+        } elseif {[regexp {Shift} $replace_key(Shift-Button-4)]} {
+          set horiz_pan_state 1
+        } else {
+          set horiz_pan_state 0
+        }
+      } 
+  
+      if {[info exist replace_key(Control-Button-4)]} {
+        if {[regexp {Control} $replace_key(Control-Button-4)]} {
+          set vert_pan_state 4
+        } elseif {[regexp {Shift} $replace_key(Control-Button-4)]} {
+          set vert_pan_state 1
+        } else {
+          set vert_pan_state 0
+        }
+      }
+
+      bind $topwin <MouseWheel> "
+        # puts \"MouseWheel: %D\"
+        if {%D > 0} {
+          # zoom in
+          xschem callback %W 4 %x %y 0 4 0 $zoom_state
+        } else {
+          # zoom out
+          xschem callback %W 4 %x %y 0 5 0 $zoom_state
+        }
+      "
+
+      bind $topwin <Shift-MouseWheel> "
+        # puts \"Shift-MouseWheel: %D\"
+        if {%D > 0} {
+          # pan to the right; move schematic to left
+          xschem callback %W 4 %x %y 0 4 0 $horiz_pan_state
+        } else {
+          # pan to the left; move schematic to right
+          xschem callback %W 4 %x %y 0 5 0 $horiz_pan_state
+        }
+      "
+
+      bind $topwin <Control-MouseWheel> "
+        # puts \"Ctrl-MouseWheel: %D\"
+        if {%D > 0} {
+          # pan down; move schematic up
+          xschem callback %W 4 %x %y 0 4 0 $vert_pan_state
+        } else {
+          # pan up; move schematic down
+          xschem callback %W 4 %x %y 0 5 0 $vert_pan_state
+        }
+      "
+
     }
 
     bind $topwin <Double-Button-1> "xschem callback %W -3 %x %y 0 %b 0 %s"