Prevent column resizing in the .NET Winforms DataGrid

Derive a new DataGrid and override the OnMouseDown method to see what portion of the grid was clicked. If it was the ColumnResize area, do not call the base class' OnMouseDown method. A new AllowColumnResizing property is added to the grid so resizing can be toggled on and off.

Add this module level variable:

    ' Column resizing flag.
    Private myAllowColumnResizing As Boolean = True

Add this property:

    Public Property AllowColumnResizing() As Boolean
        '
        ' Get/set property indicating if columns can be resized.
        '
        Get
            AllowColumnResizing = myAllowColumnResizing
        End Get

        Set(ByVal theValue As Boolean)
            myAllowColumnResizing = theValue
        End Set

    End Property

Override this method:

    Protected Overloads Overrides Sub OnMouseDown(ByVal e As MouseEventArgs)
        On Error Resume Next

        Dim aHitTestInfo As DataGrid.HitTestInfo
        aHitTestInfo = Me.HitTest(New Point(e.X, e.Y))
        '
        ' Column resizing.
        '
        If (aHitTestInfo.Type = Me.HitTestType.ColumnResize) Then
            If myAllowColumnResizing Then
                MyBase.OnMouseDown(e)
            End If
        End If

        MyBase.OnMouseDown(e)
    End Sub

Similarly, you can disable Row resizing.