Only modify focus if all previously selected nodes have been removed.

SharpTreeView/SharpTreeView.cs

@@ -151,11 +151,13 @@ namespace ICSharpCode.TreeView
 				if (selectedOldItems != null) {
 					var list = SelectedItems.Cast<SharpTreeNode>().Except(selectedOldItems).ToList();
 					SetSelectedItems(list);
+					if (SelectedItem == null) {
+						// if we removed all selected nodes, then move the focus to the node 
+						// preceding the first of the old selected nodes
+						SelectedIndex = Math.Max(0, e.OldStartingIndex - 1);
+						FocusNode((SharpTreeNode)SelectedItem);
+					}
 				}
-				// reset the focus to the previous node
-				SelectedIndex = Math.Max(0, e.OldStartingIndex - 1);
-				if (SelectedItem != null)
-					FocusNode((SharpTreeNode)SelectedItem);
 			}
 		}