I want (for some reason) make nodes in treeview checked in "one line" (i.e. in Nodes collection of any node - no more than one child could be checked). Also, latest (i.e. deepest) node should be selected. In attached example (see Example.zip): 1. Check node "Node 19" (as a result - nodes "Node 1", "Node 18" and "Node 19" checked and "Node 19" is selected). 2. Uncheck node "Node 1". Should be - nodes "Node 18" and "Node 19" checked and "Node 19" is selected. As a result - exception arised (see text of exception in Exception.zip). I suppose that it may be connected with "invisibility" of "Node 19" (I mean, if I make this actions with "Node 3" - it works fine).