Gets or sets if BarItemLinks within the current popup should be arranged in multiple columns. This is a dependency property.
true if BarItemLinks within the current popup should be arranged in multiple columns; otherwise, false.
By default, all BarItemLinks within a popup are arranged in a single column. If you want to change this behavior, you can use the MultiColumn and PopupMenuBase.MaxColumnHeight properties. The PopupMenuBase.MaxColumnHeight property specifies the maximum height of a column. If the MultiColumn property is set to true, every column will contain as many BarItemLinks as can be held without exceeding the PopupMenuBase.MaxColumnHeight property value.