DataGridView CellMouseEnter Event not working as expected

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C#2.0

C#

DataGridView

Hi all,

I have extended the DataGridView to have more features than the default control. I have added a feature that shows a PictureBox with an icon if a cell cannot display all it's contents. If the icon is clicked it changes the wrap-mode of the owning row and changes the AutoSizeRowsMode to displayed-cells.

I'm showing this icon by listening to the CellMouseEnter event and then calculating the rectangle to place the icon in the bottom right corner of the cell as follows:

if ((e.RowIndex < 0) || (e.ColumnIndex < 0))
         {   
            //_peExpand is a normal PictureBox         
            _pbExpand.Visible = false;
            return;
         }
         DataGridViewCell CellToUse = this[e.ColumnIndex, e.RowIndex];
         if (CellToUse.Size.Width < CellToUse.PreferredSize.Width)
         {
            Rectangle DisplayRect = this.GetCellDisplayRectangle(e.ColumnIndex, 
            e.RowIndex, false);            
            _pbExpand.Location = new Point(DisplayRect.Right -   
            _pbExpand.Image.Width, DisplayRect.Bottom - _pbExpand.Image.Height);            
            _pbExpand.Tag = CellToUse;
            _pbExpand.Visible = true;
            _pbExpand.Image = (CellToUse.OwningRow.DefaultCellStyle.WrapMode == 
            DataGridViewTriState.True) ? Resources.chevron_icon :   
            Resources.chevron_expand_icon;            
         }

My problem comes after the row has been expanded and the mouse pointer leaves the cell and enters again later. It ignores the PictureBox (it's still drawn to the correct place). If I hold the mouse pointer over the PictureBox then it fires the CellMouseEnter event hundreds of times instead of firing the MouseEnter event for the PictureBox. It works perfectly fine if the row is expanded and the pointer never leaves the cell. If anyone can point me in the right direction I would appreciate it.

Edit: It only seems to happen when the DataGridView property AutoSizeRowsMode is set to DisplayedCells. It also seems to happen only when there is a control on the cell & the mouse pointer enters that control.