I have a reproducible exception that is thrown by an UltraGrid when the mouse scroll is used on a cell that does not support mouse scroll (like a regular text field).
I am able to reproduce this problem by peforming the following steps:
1. Ensure that the Grid AfterCellUpdate event has a call to DataBind().
2. Select a value in a "DropdownList" grid cell that has a value list.
3. Go to a different normal text cell and use the mouse scroll wheel (mine happens to have an input mask on it).
4. Object ref error is thrown.
I have seen other problems with grids before when a DataBind() is called within certain events. I assume that a ton of things are put into motion when a DataBind() is called....
The stack trace is like so:
Exception=System.NullReferenceException: Object reference not set to an instance of an object. at Infragistics.Win.EditorWithCombo.ProcessOnMouseWheel(MouseEventArgs e) at Infragistics.Win.EditorWithCombo.OnOwningControlMouseWheel(Object sender, MouseEventArgs e) at System.Windows.Forms.MouseEventHandler.Invoke(Object sender, MouseEventArgs e) at System.Windows.Forms.Control.OnMouseWheel(MouseEventArgs e) at Infragistics.Win.UltraWinGrid.UltraGridBase.OnMouseWheel(MouseEventArgs e) at System.Windows.Forms.Control.WmMouseWheel(Message& m) at System.Windows.Forms.Control.WndProc(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.OnMessage(Message& m) at System.Windows.Forms.Control.ControlNativeWindow.WndProc(Message& m) at System.Windows.Forms.NativeWindow.Callback(IntPtr hWnd, Int32 msg, IntPtr wparam, IntPtr lparam)
Are you calling DataBind() on the grid itself? You should not need to do this as the grid implicitly binds itself to the DataSource when set. If you want to force the grid to reload the data, you could call "this.ultraGrid1.Rows.Refresh(RefreshRow.ReloadData);". Is there something else that you need that is leading you to call DataBind()?
-Matt
As an update, I tried out your steps and wasn't able to reproduce the problem so it's also possible that it was fixed in the latest hotfix.