Hi Michael,

Your idea of using a fake summary row (or data row) is not bad. But as you noticed, you cannot catch mouse events on the dropdown portion of the combo - at least not easily.

I found a way to do this using a CreationFilter to insert a custom button UIElement into the dropdown.

So I add a fake summary to the combo:

        private void ultraCombo1_InitializeLayout(object sender, InitializeLayoutEventArgs e)
        {
            UltraGridLayout layout = e.Layout;
            UltraGridBand band = layout.Bands[0];
            UltraGridOverride ov = layout.Override;

            band.Summaries.Add("Fake", null);
            ov.SummaryFooterCaptionVisible = DefaultableBoolean.False;
        }

And I create a class which inherits from ButtonUIElement and override the OnClick method.

    internal class ComboLoadMoreDataButtonUIElement : ButtonUIElement
    {
        public ComboLoadMoreDataButtonUIElement(UIElement parent)
            : base(parent)
        { }

        protected override void OnClick()
        {
            base.OnClick();
        }
    }

Then I create a CreationFilter class that watches for the SummaryFooterUIElement and replaces the entire contents of this element with my custom button element.

    
    internal class ComboLoadMoreDataCreationFilter : IUIElementCreationFilter
    {
        #region IUIElementCreationFilter Members

        void IUIElementCreationFilter.AfterCreateChildElements(UIElement parent)
        {
            // do nothing
        }

        bool IUIElementCreationFilter.BeforeCreateChildElements(UIElement parent)
        {
            SummaryFooterUIElement summaryFooterUIElement = parent as SummaryFooterUIElement;
            if (summaryFooterUIElement != null)
            {
                ComboLoadMoreDataButtonUIElement comboLoadMoreDataButtonUIElement = null;

                // See if there is an existing element we can re-use. 
                if (parent.ChildElements.Count > 0)
                {
                    foreach (UIElement childElement in parent.ChildElements)
                    {
                        if (childElement is ComboLoadMoreDataButtonUIElement)
                        {
                            comboLoadMoreDataButtonUIElement = (ComboLoadMoreDataButtonUIElement)childElement;
                            break;
                        }
                    }
                }

                parent.ChildElements.Clear();

                if (comboLoadMoreDataButtonUIElement == null)
                    comboLoadMoreDataButtonUIElement = new ComboLoadMoreDataButtonUIElement(parent);

                comboLoadMoreDataButtonUIElement.Rect = parent.Rect;
                parent.ChildElements.Add(comboLoadMoreDataButtonUIElement);
                return true;
            }

            return false;
        }

        #endregion
    }

And you just have to attach the CreationFilter to the combo up front. I'd do this in Form_Load.

            this.ultraCombo1.CreationFilter = new ComboLoadMoreDataCreationFilter();

Few points though.

I need a mechanism to communicate bewteen this UIElement and the UltraCombo for things like,

• getting the colours from the styleset of the UltraCombo ; at the moment I'm using hard coded values
• getting information about the rows so I can figure out what to display  - e.g. "displaying 25 of 80 "
• sending the click event up to the UltraCombo so it can do something to get the next bit of data

At the moment I can do all of the above by tweaking the constructors of the CreationFilter and uielement to pass in the UltraCombo - it just feels a little bit of a hack.

Also the fake button doesnt actually behave like a button, i.e. I don't see it looking pressed when I click on it. I don't need that functionality (in fact i may make mine look like a hyperlink), but is more for completeness for anyone else reading this.

thanks

Michael

All combinations of Invalidate, DoEvents don't help. The also the GUi isnt locked, we can still type and clicking on say the (real) scrollbar causes the old data to dissapear.

If I completely get rid of the above override and don't have a button then there is no problem and the old data dissapears.

thanks

Michael

Hope you can see green lines (just one pixel) just inside the white borders. In any case this was a first try, I had thoughts of showing/hiding top/left/right borders.

Looks like DrawFilter is the way, can you give me a pointer as to how to isolate the bottom grid using this method

thanks

Michael