Infragistics.WebUI.UltraWebNavigator Namespace > UltraWebMenu Class : XPSpacerWidth Property

"Returns or sets a Unit value that determines the width of the spacer column on the left side of the menu. This property is used in conjunction with the WebMenuStyle.XPClient property setting and the XPSpacerImage property. The image column is used as a background for images displayed within the menu."

Correction:  This property is used to set the width in modes other than just XP.  For example, if you want to adjust the margin to the left of a menu item in WebStandard mode, you MUST set that width via Images-XPSpacerImage-Width

Infragistics.WebUI.UltraWebNavigator Namespace > UltraWebMenu Class : TopItemSpacing Property

"This property controls the alignment of menu items at the top level.
When true, items are evenly spaced right to left for horizontal menus and evenly spaced top to bottom for vertical menus.
When false, items are aligned against the left edge for horizontal menus and against the top edge for veritical menus."

True and False are INVALID values for this property.
Correct values are Auto or Compact.