PreferredDropDownColumns プロパティ

using System.Windows.Forms;
using Infragistics.Win.UltraWinToolbars;

private void button1_Click( object sender, EventArgs e )
{
	// Get the gallery from the toolbars manager which will be customized
	PopupGalleryTool gallery = (PopupGalleryTool)this.ultraToolbarsManager1.Tools[ "PopupGalleryTool1" ];

	// Set the appearance of the filter bar in the gallery drop down.
	gallery.FilterBarAppearance.BackColor = Color.Orange;
	gallery.FilterBarAppearance.BackColor2 = Color.Yellow;
	gallery.FilterBarAppearance.BackGradientStyle = Infragistics.Win.GradientStyle.GlassTop37;

	// Set the appearance of the filter bar when the mouse is over it in the gallery drop down
	gallery.HotTrackFilterBarAppearance.ForeColor = Color.White;

	// Leave 15 pixels between the left edge of the drop down and the items in a group.
	gallery.GroupItemAreaPadding.Left = 15;

	// Set the appearance of the area behind the items in all groups of the gallery drop down
	gallery.GroupSettings.ItemAreaAppearance.BackColor = Color.LightGray;

	// Leave 10 pixels below each item in the gallery drop down and preview
	gallery.ItemPadding.Bottom = 10;

	// Set the display of selected items to select the image only.  For items to be selected,
	// the ItemStyle must be set to StateButton.
	// Note: With this selection display style, if there is no image, the selection will not be displayed.
	gallery.ItemStyle = ItemStyle.StateButton;
	gallery.ItemSettings.SelectionDisplayStyle = SelectionDisplayStyle.HighlightImageOnly;

	// Set the size of the items in the drop down and preview separately.  If these size are not
	// set, the size will be calculated automatically based on the contents of all items.
	gallery.ItemSizeInDropDown = new Size( 50, 50 );
	gallery.ItemSizeInPreview = new Size( 25, 25 );

	// Set the min, max, and preferred drop down columns.  If the min and max are the same, the gallery
	// drop down will only be resizable vertically.
	// Note: If UltraToolbarsManager.Office2007UICompatibility is true, these values may be increased
	// so the gallery drop down always occludes the gallery preview.
	gallery.MinDropDownColumns = 2;
	gallery.PreferredDropDownColumns = 3;
	gallery.MaxDropDownColumns = 8;

	// Set the min and max gallery preview columns.  When resizing the ribbon smaller, if the min columns can
	// no longer fit, the gallery will be changed to a gallery drop down button (if it is smaller).
	gallery.MinPreviewColumns = 3;
	gallery.MaxPreviewColumns = 5;

	// Set the appearance of the gallery preview in the ribbon
	gallery.PreviewItemAreaAppearance.BackColor = Color.LightYellow;
	gallery.PreviewItemAreaAppearance.BackColor2 = Color.SkyBlue;
	gallery.PreviewItemAreaAppearance.BackGradientStyle = Infragistics.Win.GradientStyle.VerticalBump;

	// Set the appearance of the hot tracked gallery preview in the ribbon
	gallery.HotTrackPreviewItemAreaAppearance.BackColor = Color.SkyBlue;
	gallery.HotTrackPreviewItemAreaAppearance.BackColor2 = Color.LightYellow;
	gallery.HotTrackPreviewItemAreaAppearance.BackGradientStyle = Infragistics.Win.GradientStyle.VerticalBump;

	// Set the ShowItemText to Always so the text of gallery items display their titles and descriptions.
	// Note: For the Always setting to take affect, UltraToolbarsManager.Office2007UICompatibility must
	// be false.  Otherwise, it will automatically be resolved to OnlyInDropDown.
	gallery.ToolbarsManager.Office2007UICompatibility = false;
	gallery.ShowItemText = ShowGalleryItemText.Always;
}