The DataGridView doesn't do editing like Excel where the textbox grows larger when you add more text. You might be able to perform some advanced customziation. Check out the PositionEditingControl and PositionEditingPanel methods on DataGridViewCell. You will also need to return true from the RepositionEditingControlOnValueChange property on IDataGridViewEditingControl interface.

-mark
DataGridView Program Manager
Microsoft
This post is provided "as-is"

The DataGridViewCell::PositionEditingControl and DataGridViewCell::PositionEditingPanel are virtual/overridable method. You need to sub-class the DataGridViewCell in order to get access (override) this method.  See http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vbcn7/html/vaconInheritanceForBasicLanguage.asp for details on sub-classing using Visual Basic.

Note in your case you will want to sub-class the DataGridViewTextBoxCell.
 
Here is some code that will help:

Public Class Form1     Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load         Dim c As DataGridViewTextBoxColumn = New DataGridViewTextBoxColumn()         c.CellTemplate = New EditableMergedCell()         dataGridView1.Columns.Add(c)         c = New DataGridViewTextBoxColumn()         dataGridView1.Columns.Add(c)         dataGridView1.RowCount = 10     End Sub End Class Public Class EditableMergedCell     Inherits DataGridViewTextBoxCell     Public Overrides Sub PositionEditingControl(ByVal setLocation As Boolean, ByVal setSize As Boolean, ByVal cellBounds As System.Drawing.Rectangle, ByVal cellClip As System.Drawing.Rectangle, ByVal cellStyle As System.Windows.Forms.DataGridViewCellStyle, ByVal singleVerticalBorderAdded As Boolean, ByVal singleHorizontalBorderAdded As Boolean, ByVal isFirstDisplayedColumn As Boolean, ByVal isFirstDisplayedRow As Boolean)         MyBase.PositionEditingControl(setLocation, setSize, cellBounds, cellClip, cellStyle, singleVerticalBorderAdded, singleHorizontalBorderAdded, isFirstDisplayedColumn, isFirstDisplayedRow)     End Sub     Public Overrides Function PositionEditingPanel(ByVal cellBounds As System.Drawing.Rectangle, ByVal cellClip As System.Drawing.Rectangle, ByVal cellStyle As System.Windows.Forms.DataGridViewCellStyle, ByVal singleVerticalBorderAdded As Boolean, ByVal singleHorizontalBorderAdded As Boolean, ByVal isFirstDisplayedColumn As Boolean, ByVal isFirstDisplayedRow As Boolean) As System.Drawing.Rectangle         ' the cell rectangle is the bounds of the merged cell         Dim mergedRectangle As Rectangle = New Rectangle(cellBounds.Location, New Size(cellBounds.Width * 2, cellBounds.Height))         ' the cell clip tells the grid how much of the merged cell is visible.         Dim mergedCellClip As Rectangle = New Rectangle(cellClip.Location, New Size(cellClip.Width * 2, cellClip.Height))         ' -------------------         ' NOTE: This is how the grid determins the cell clip by default:         'Dim cellClip as Rectangle = cellBounds         '// Need to clip the zones of the frozen columns and rows and headers.         'If (not me.Columns(this.ptCurrentCell.X).Frozen) then         '         '    Dim totalVisibleFrozenWidth as Integer = me.Columns.GetColumnsWidth(DataGridViewElementStates.Visible or DataGridViewElementStates.Frozen)         '    If (not me.RightToLeftInternal) Then         '        editingZone.X += totalVisibleFrozenWidth         '    End If         '    editingZone.Width = Math.Max(0, editingZone.Width - totalVisibleFrozenWidth)         'End If         'If ((me.Rows.GetRowState(this.ptCurrentCell.Y) and DataGridViewElementStates.Frozen) = 0) Then         '    Dim totalVisibleFrozenHeight as Integer = me.Rows.GetRowsHeight(DataGridViewElementStates.Visible or DataGridViewElementStates.Frozen)         '    editingZone.Y += totalVisibleFrozenHeight         'End If         'cellClip.Intersect(editingZone)         '---------------------------         Return MyBase.PositionEditingPanel(cellBounds, cellClip, cellStyle, singleVerticalBorderAdded, singleHorizontalBorderAdded, isFirstDisplayedColumn, isFirstDisplayedRow)     End Function End Class

-mark
DataGridView Program Manager
Microsoft
This post is provided "as-is"

The DataGridView doesn't do editing like Excel where the textbox grows larger when you add more text. You might be able to perform some advanced customziation. Check out the PositionEditingControl and PositionEditingPanel methods on DataGridViewCell. You will also need to return true from the RepositionEditingControlOnValueChange property on IDataGridViewEditingControl interface.

-mark
DataGridView Program Manager
Microsoft
This post is provided "as-is"

The DataGridViewCell::PositionEditingControl and DataGridViewCell::PositionEditingPanel are virtual/overridable method. You need to sub-class the DataGridViewCell in order to get access (override) this method.  See http://msdn.microsoft.com/library/default.asp?url=/library/en-us/vbcn7/html/vaconInheritanceForBasicLanguage.asp for details on sub-classing using Visual Basic.

Note in your case you will want to sub-class the DataGridViewTextBoxCell.
 
Here is some code that will help:

Public Class Form1     Private Sub Form1_Load(ByVal sender As System.Object, ByVal e As System.EventArgs) Handles MyBase.Load         Dim c As DataGridViewTextBoxColumn = New DataGridViewTextBoxColumn()         c.CellTemplate = New EditableMergedCell()         dataGridView1.Columns.Add(c)         c = New DataGridViewTextBoxColumn()         dataGridView1.Columns.Add(c)         dataGridView1.RowCount = 10     End Sub End Class Public Class EditableMergedCell     Inherits DataGridViewTextBoxCell     Public Overrides Sub PositionEditingControl(ByVal setLocation As Boolean, ByVal setSize As Boolean, ByVal cellBounds As System.Drawing.Rectangle, ByVal cellClip As System.Drawing.Rectangle, ByVal cellStyle As System.Windows.Forms.DataGridViewCellStyle, ByVal singleVerticalBorderAdded As Boolean, ByVal singleHorizontalBorderAdded As Boolean, ByVal isFirstDisplayedColumn As Boolean, ByVal isFirstDisplayedRow As Boolean)         MyBase.PositionEditingControl(setLocation, setSize, cellBounds, cellClip, cellStyle, singleVerticalBorderAdded, singleHorizontalBorderAdded, isFirstDisplayedColumn, isFirstDisplayedRow)     End Sub     Public Overrides Function PositionEditingPanel(ByVal cellBounds As System.Drawing.Rectangle, ByVal cellClip As System.Drawing.Rectangle, ByVal cellStyle As System.Windows.Forms.DataGridViewCellStyle, ByVal singleVerticalBorderAdded As Boolean, ByVal singleHorizontalBorderAdded As Boolean, ByVal isFirstDisplayedColumn As Boolean, ByVal isFirstDisplayedRow As Boolean) As System.Drawing.Rectangle         ' the cell rectangle is the bounds of the merged cell         Dim mergedRectangle As Rectangle = New Rectangle(cellBounds.Location, New Size(cellBounds.Width * 2, cellBounds.Height))         ' the cell clip tells the grid how much of the merged cell is visible.         Dim mergedCellClip As Rectangle = New Rectangle(cellClip.Location, New Size(cellClip.Width * 2, cellClip.Height))         ' -------------------         ' NOTE: This is how the grid determins the cell clip by default:         'Dim cellClip as Rectangle = cellBounds         '// Need to clip the zones of the frozen columns and rows and headers.         'If (not me.Columns(this.ptCurrentCell.X).Frozen) then         '         '    Dim totalVisibleFrozenWidth as Integer = me.Columns.GetColumnsWidth(DataGridViewElementStates.Visible or DataGridViewElementStates.Frozen)         '    If (not me.RightToLeftInternal) Then         '        editingZone.X += totalVisibleFrozenWidth         '    End If         '    editingZone.Width = Math.Max(0, editingZone.Width - totalVisibleFrozenWidth)         'End If         'If ((me.Rows.GetRowState(this.ptCurrentCell.Y) and DataGridViewElementStates.Frozen) = 0) Then         '    Dim totalVisibleFrozenHeight as Integer = me.Rows.GetRowsHeight(DataGridViewElementStates.Visible or DataGridViewElementStates.Frozen)         '    editingZone.Y += totalVisibleFrozenHeight         'End If         'cellClip.Intersect(editingZone)         '---------------------------         Return MyBase.PositionEditingPanel(cellBounds, cellClip, cellStyle, singleVerticalBorderAdded, singleHorizontalBorderAdded, isFirstDisplayedColumn, isFirstDisplayedRow)     End Function End Class

-mark
DataGridView Program Manager
Microsoft
This post is provided "as-is"

This is my implementation. There seems to be a few problems with wrapping but.

public class MemoCell: DataGridViewTextBoxCell

{

public override void InitializeEditingControl(int rowIndex, object initialFormattedValue, DataGridViewCellStyle dataGridViewCellStyle)

{

dataGridViewCellStyle.WrapMode = DataGridViewTriState.True;

base.InitializeEditingControl(rowIndex, initialFormattedValue, dataGridViewCellStyle);

}

public override void PositionEditingControl(bool setLocation, bool setSize, Rectangle cellBounds, Rectangle cellClip, DataGridViewCellStyle cellStyle, bool singleVerticalBorderAdded, bool singleHorizontalBorderAdded, bool isFirstDisplayedColumn, bool isFirstDisplayedRow)

{

base.PositionEditingControl(setLocation, setSize, cellBounds, cellClip, cellStyle, singleVerticalBorderAdded, singleHorizontalBorderAdded, isFirstDisplayedColumn, isFirstDisplayedRow);

}

public override Rectangle PositionEditingPanel(Rectangle cellBounds, Rectangle cellClip, DataGridViewCellStyle cellStyle, bool singleVerticalBorderAdded, bool singleHorizontalBorderAdded, bool isFirstDisplayedColumn, bool isFirstDisplayedRow)

{

string value = (string)this.EditedFormattedValue;

Size maxSize = MaxSize(cellBounds.Location);

Size stringSize = MeasureString(value, cellStyle.Font, new SizeF((float)maxSize.Width, (float)maxSize.Height));

Console.WriteLine(stringSize);

Rectangle maxRectangle = new Rectangle(cellBounds.Location, MaxSize(cellBounds.Location));

int finalWidth = Math.Max(stringSize.Width, cellBounds.Width);

int finalHeight = Math.Max(stringSize.Height, cellBounds.Height);

Rectangle finalRectangle = new Rectangle(cellBounds.Location, new Size(finalWidth, finalHeight));

return base.PositionEditingPanel(finalRectangle, finalRectangle, cellStyle, singleVerticalBorderAdded, singleHorizontalBorderAdded, isFirstDisplayedColumn, isFirstDisplayedRow);

}

public override Type EditType

{

get

{

return typeof(MemoTextBox);

}

}

public Size MeasureString(string value, Font font, SizeF layoutArea)

{

int characters,lines;

int lineHeight;

Graphics g = Graphics.FromHwnd(this.DataGridView.Handle);

lineHeight = g.MeasureString("MeasureString", font).ToSize().Height;

Size size = g.MeasureString(value, font, layoutArea, new StringFormat(StringFormatFlags.MeasureTrailingSpaces), out characters, out lines).ToSize();

Console.WriteLine("Characters{0}, lines{1}", characters, lines);

if (value.EndsWith(Environment.NewLine))

{

lines += 1;

}

size.Height = (lineHeight * lines);

return size;

}

private Size MaxSize(Point relativeLocation)

{

Size gridSize = this.DataGridView.Size;

int widthLeftover = gridSize.Width - relativeLocation.X;

int heightLeftover = gridSize.Height - relativeLocation.Y;

if (widthLeftover < 0

|| heightLeftover < 0)

{

throw new Exception("Tp can't be right!");

}

return new Size(widthLeftover, heightLeftover);

}

}