Hello, Martin,    

I really appreciate the provided feedback as it is helpful for making UI for WinForms a better product. However, please note that RadGridView is a complex control that provides a great diversity of features. Hence, its internal implementation is not always manageable according to all requests that our customers have. Even though we strive to provide as good public API as possible, there are numerous factors and core implementation that affect the API. Sometimes these factors are not obvious to the customers and we provide solid explanation how a certain functionality works. When it comes to creating a custom control deriving from RadGridView, it is better to contact the Telerik WinForms support and share what is the exact goal that you are trying to achieve than to create the custom implementation assuming that it works in a specific way. Thus, we can provide guidance how to accomplish a certain task. 

Now, I will go straight to previously listed topics:

1. I understand the convention you are referring to and I believe it is followed here:

The CreateRowInfo event is available for the RadGridView control and for its MasterTemplate:

	    _grid = new RadGridViewPlus();
            _grid.CreateRowInfo += _grid_CreateRowInfo;
            _grid.MasterTemplate.CreateRowInfo += MasterTemplate_CreateRowInfo;

If you handle the MasterTemplate.CreateRowInfo event and replace the newly added row via the new row UI, it is correctly replaced:

        private void MasterTemplate_CreateRowInfo(object sender, GridViewCreateRowInfoEventArgs e)
        {
			if (e.RowInfo is GridViewDataRowInfo)
			{
				e.RowInfo = new GridViewDataRowInfoPlus(e.ViewInfo);
			}
		}

The RadGridView.CreateRowInfo event is not used here.

        private void _grid_CreateRowInfo(object sender, GridViewCreateRowInfoEventArgs e)
        {
           
        }

2. I believe that 1. gives you the appropriate API that you can use in this scenario.

3. I agree that it is not a generic approach as it should be adopted to the specific DataSource collection that is assigned to the grid. The UserAddingRow event is commonly used for validating the data inside the new row before coming it to the grid. Thus, cancelling the UserAddingRow event will prevent the row to be added as a data row. More information on this topic is available here:
https://docs.telerik.com/devtools/winforms/controls/gridview/rows/new-row#user-events 

4. The internal workflow when using the new row UI handles the new row via the OnCreateRowInfo method of the MasterTemplate, not the OnCreateRowInfo method of the RadGridView itself. That is why there are events  at RadGridView level that are specifically introduced for handling the new row UI: UserAddingRow and UserAddedRow. They are documented in the online docs article referred above. These events were introduced a very long time ago and they are still serving the purposes that most of our customers have.

5. Thank you for filling the roadmap survey. It will definitely add value to the future planning of the product. As to the difficulties that you may experience during the development process, note that we are always here to help. The Telerik Technical Support is well familiar with the product and  how it is implemented. So if you have any difficulties or need some guidance, feel free to contact us and we will gladly assist you.

I hope that you will find the provided information useful.

Regards,
Dess | Tech Support Engineer, Principal
Progress Telerik

	public class RadGridViewPlus: RadGridView
	{
		public RadGridViewPlus()
		{
			ThemeClassName = typeof(RadGridView).FullName;
		}

		protected override void OnCreateRowInfo(object sender, GridViewCreateRowInfoEventArgs e)
		{
			base.OnCreateRowInfo(sender, e);
			if (e.RowInfo is GridViewDataRowInfo)
				e.RowInfo = new GridViewDataRowInfoPlus(e.ViewInfo);
		}
	}

Indeed, the OnCreateRowInfo method that RadGridView offers is not called when you are manually adding a new row to the grid as different internal logic is performed. However, I would like to note that the appropriate ways to replace the default GridViewDataRowInfo instances with your custom ones is to subscribe to the CreateRowInfo event that RadGridView offers. While the new row UI is used, the grid control suspends its notifications and the CreateRowInfo event wouldn't be fired until resuming the suspended notifications. A specific event for handling adding the new row via the UI is the UserAddingRow event. Thus, you can cancel the default row and add programmatically a new record to the assigned DataSource:

        private void _grid_UserAddingRow(object sender, GridViewRowCancelEventArgs e)
        {
			e.Cancel = true; 
			DataTable dt = e.Rows[0].ViewTemplate.DataSource as DataTable;
			DataRow dr=dt.NewRow();
			foreach (GridViewCellInfo cell in e.Rows[0].Cells)
			{
				dr[cell.ColumnInfo.Name] = cell.Value;
			}
			dt.Rows.Add(dr);
		}

Thus, the desired custom row will be created:

An alternative solution that I can suggest is to use the following approach: 

public class RadGridViewPlus: RadGridView
{
	public RadGridViewPlus()
	{
		ThemeClassName = typeof(RadGridView).FullName;
	} 

    protected override RadGridViewElement CreateGridViewElement()
    {
        return new CustomRadGridViewElement();
    }
}

public class CustomRadGridViewElement: RadGridViewElement
{
    protected override MasterGridViewTemplate CreateTemplate()
    {
        return new CustomMasterGridViewTemplate();
    } 
}

public class CustomMasterGridViewTemplate : MasterGridViewTemplate
{
    protected override void OnCreateRowInfo(GridViewCreateRowInfoEventArgs e)
    {
        base.OnCreateRowInfo(e);
        if (e.RowInfo is GridViewDataRowInfo)
            e.RowInfo = new GridViewDataRowInfoPlus(e.ViewInfo);
    }
}

Feel free to use this approach which suits your requirements best.

Regards,
Dess | Tech Support Engineer, Principal
Progress Telerik

Hello, Martin,

I am sorry to hear that you are experiencing any difficulties with the Telerik Ui for WinForms suite and the RadGridView control.

You should subscribe to the CreateRowInfo event at design time in order to ensure that the event will be fired when a data row have to be created. A sample approach for creating custom data rows is demonstarted here: https://docs.telerik.com/devtools/winforms/controls/gridview/rows/creating-custom-rows 

Could you please specify whether you are using a similar approach? It would be greatly appreciated if you can provide a sample runnable project demonstrating the undesired behavior that you are facing. Thus, we would be able to make an adequate analysis of the precise case and provide further assistance.

Thank you in advance for your cooperation. I am looking forward to your reply.

Regards,
Dess | Tech Support Engineer, Principal
Progress Telerik