property Surface.SingleSel as Boolean
Returns or sets a value that indicates whether the user can select one or more objects.

TypeDescription
Boolean A Boolean expression that specifies whether the control supports single or multiple selection.
By default, the SingleSel property is False, which indicates that multiple elements can be selected. The SingleSel property specifies whether the surface allows selecting one or multiple elements. The Selectable property of the Element object indicates whether the element is selectable or un-selectable. The SelCount property counts the number of selected elements. The SelElement property returns the selected element based on its index in the selected elements collection. The Selection property sets or gets a safe array of selected elements. The SelectionChanged event occurs once a new element is selected or unselected. The Selected property of the Element object indicates whether the element is selected or unselected. The SelectAll method selects all elements in the chart. Use the UnselectAll method to unselect all elements on the surface. Use the AllowMoveSelection property to prevent moving the entire selection when focused element is moved. Use the AllowResizeSelection property to prevent resizing the entire selection when focused element is resized. Use the AllowMoveDescendents  property to prevent moving all descendents ( children and outgoing elements ) when focused element is moved. The HideSel property specifies whether the selected elements are highlighted or not when the control loses the focus.

The SelectObjectColor / SelectObjectTextColor property specifies the colors to show the selected elements ( while the control has the focus ). The SelectObjectColorInactive / SelectObjectTextColorInactive property specifies the color to show the selected elements ( while the control is not focused ). The SelectObjectStyle property specifies the style to show the selected elements ( like changing the element's background/foreground colors, showing a border around the selected elements, and so on ). Use the Background(exSelectObjectRectColor) property to specify the color to show the rectangle that highlights the elements that intersect the dragging rectangle.

The AllowSelectObject property indicates the keys combination to allow user selecting new elements. The AllowSelectObjectRect property specifies the keys combination so the user can select the elements from the dragging rectangle. The AllowSelectNothing property indicates whether the selection is cleared once the user clicks any empty area on the surface.