diff --git a/src/MainForm.cs b/src/MainForm.cs
index 9a9e037..a0efe06 100644
--- a/src/MainForm.cs
+++ b/src/MainForm.cs
@@ -25,6 +25,7 @@ public partial class MainForm : Form
 
     private Point? mMouseDragAnchor = null ;
     private Tuple<int,int> mScrollDragAnchor ;
+    private double mUserZoom = 1.0 ;
 
     public MainForm()
     {
diff --git a/src/MainForm.ui.cs b/src/MainForm.ui.cs
index 6d7d0be..631bdff 100644
--- a/src/MainForm.ui.cs
+++ b/src/MainForm.ui.cs
@@ -104,17 +104,22 @@ public partial class MainForm : Form
         return false ;
     }
 
+    private int ChartImagePanel_MaxScrollX() { return mChartImagePanel.HorizontalScroll.Maximum - mChartImagePanel.Width + 17 ; }
+    private int ChartImagePanel_MaxScrollY() { return mChartImagePanel.VerticalScroll.Maximum - mChartImagePanel.Height + 17 ; }
+
     private void MainForm_Load( object sender, EventArgs e )
     {
         // initialize
-        MainForm_Resize( this, null ) ;
+        doMainFormResize( null ) ;
 
         // load the chart images
         loadChartImages() ;
         loadSearchResults( mChartImages.Values ) ;
     }
 
-    private void MainForm_Resize( object sender, EventArgs e )
+    private void MainForm_Resize( object sender, EventArgs e ) { doMainFormResize( null ) ; }
+
+    private void doMainFormResize( Point? clientMousePos )
     {
         // check if we are showing a ChartImage
         Image img = mChartImagePictureBox.Image ;
@@ -149,6 +154,10 @@ public partial class MainForm : Form
             height = (int) (img.Height * maxZoom) ;
         }
 
+        // incorporate the user-controlled manual zoom
+        width = (int)( width * mUserZoom + 0.5 ) ;
+        height = (int)( height * mUserZoom + 0.5 ) ;
+
         // check if the v-scrollbar is showing
         if ( height >= mChartImagePanel.Height ) {
             // yup - adjust the width
@@ -157,16 +166,44 @@ public partial class MainForm : Form
             width -= sbWidth ;
         }
 
+        // remember the current scroll positions
+        HScrollProperties hscroll = mChartImagePanel.HorizontalScroll ;
+        int prevScrollPosX = hscroll.Value ;
+        int prevMaxScrollX = ChartImagePanel_MaxScrollX() ;
+        double prevRelScrollPosX = (double)prevScrollPosX / (double)prevMaxScrollX ;
+        VScrollProperties vscroll = mChartImagePanel.VerticalScroll ;
+        int prevScrollPosY = vscroll.Value ;
+        int prevMaxScrollY = ChartImagePanel_MaxScrollY() ;
+        double prevRelScrollPosY = (double)prevScrollPosY / (double)prevMaxScrollY ;
+
         // resize and position the ChartImage
-        // TODO: It would be nice to maintain the scroll position of the current image,
-        // but how .NET sets the scroll range/position is weird :-/
+        mChartImagePanel.HorizontalScroll.Value = 0 ;
+        mChartImagePanel.VerticalScroll.Value = 0 ;
+        Size prevChartImagePictureBoxSize = new Size( mChartImagePictureBox.Size.Width, mChartImagePictureBox.Size.Height ) ;
         mChartImagePictureBox.Size = new Size( width, height ) ;
         if ( width < availableWidth )
             mChartImagePictureBox.Location = new Point( margin + (availableWidth - width)/2, margin ) ;
         else
             mChartImagePictureBox.Location = new Point( margin, margin ) ;
-        mChartImagePanel.HorizontalScroll.Value = 0 ;
-        mChartImagePanel.VerticalScroll.Value = 0 ;
+
+        // restore the scroll positions
+        int newScrollPosX, newScrollPosY ;
+        int newMaxScrollX = ChartImagePanel_MaxScrollX() ;
+        int newMaxScrollY = ChartImagePanel_MaxScrollY() ;
+        if ( clientMousePos == null ) {
+            // maintain the relative scroll positions
+            newScrollPosX = (int)( prevRelScrollPosX * newMaxScrollX + 0.5 ) ;
+            newScrollPosY = (int)( prevRelScrollPosY * newMaxScrollY + 0.5 ) ;
+        } else {
+            // keep whatever's under the mouse in the same place
+            int absX = prevScrollPosX + clientMousePos.Value.X ;
+            double scaling = (double)mChartImagePictureBox.Size.Width / (double)prevChartImagePictureBoxSize.Width ;
+            newScrollPosX = (int)( absX * scaling + 0.5) - clientMousePos.Value.X ;
+            int absY = prevScrollPosY + clientMousePos.Value.Y ;
+            scaling = (double)mChartImagePictureBox.Size.Height / (double)prevChartImagePictureBoxSize.Height ;
+            newScrollPosY = (int)( absY * scaling + 0.5) - clientMousePos.Value.Y ;
+        }
+        scrollChartImagePanel( newScrollPosX, newScrollPosY ) ;
     }
 
     private void ChartImagePictureBox_MouseDown( object sender, MouseEventArgs e )
@@ -213,6 +250,15 @@ public partial class MainForm : Form
             int scrollRange = hscroll.Maximum - hscroll.Minimum ;
             int scrollX = hscroll.Value + (int)( scrollRange * nLines/100 ) ;
             scrollChartImagePanel( scrollX, null ) ;
+        } else if ( (Control.ModifierKeys & Keys.Control) != 0 ) {
+            if ( nLines > 0 ) {
+                float maxUserZoom = Program.appConfig.getFloatVal( new string[]{"MaxUserZoom"}, 2.0f ) ;
+                mUserZoom = Math.Min( mUserZoom+0.1, maxUserZoom ) ;
+            } else {
+                float minUserZoom = Program.appConfig.getFloatVal( new string[]{"MinUserZoom"}, 0.5f ) ;
+                mUserZoom = Math.Max( mUserZoom-0.1, minUserZoom ) ;
+            }
+            doMainFormResize( pos ) ;
         } else {
             // scroll the ChartImage up/down
             VScrollProperties vscroll = mChartImagePanel.VerticalScroll ;
@@ -227,14 +273,14 @@ public partial class MainForm : Form
         // update the scroll position
         if ( scrollX != null ) {
             HScrollProperties hscroll = mChartImagePanel.HorizontalScroll ;
-            int maxScrollX = hscroll.Maximum - mChartImagePanel.Width + 17 ;
+            int maxScrollX = ChartImagePanel_MaxScrollX() ;
             int scrollPos = Math.Max( 0, Math.Min( maxScrollX, scrollX.Value ) ) ;
             hscroll.Value = scrollPos ;
             hscroll.Value = scrollPos ; // nb: for Windows :shrug:
         }
         if ( scrollY != null ) {
             VScrollProperties vscroll = mChartImagePanel.VerticalScroll ;
-            int maxScrollY = vscroll.Maximum - mChartImagePanel.Height + 17 ;
+            int maxScrollY = ChartImagePanel_MaxScrollY() ;
             int scrollPos = Math.Max( 0, Math.Min( maxScrollY, scrollY.Value ) ) ;
             vscroll.Value = scrollPos ;
             vscroll.Value = scrollPos ; // nb: for Windows :shrug:
@@ -253,7 +299,8 @@ public partial class MainForm : Form
             mChartImagePictureBox.Image = null ;
         mChartImagePanel.HorizontalScroll.Value = 0 ;
         mChartImagePanel.VerticalScroll.Value = 0 ;
-        MainForm_Resize( this, null ) ;
+        mUserZoom = 1.0 ;
+        doMainFormResize( null ) ;
     }
 
     private void SearchQuery_TextChanged( object sender, EventArgs e )