TreeView was fixed

TreeView did had some changes in it's code and they were mostly to overcome some design issues regarding face splitter in general and making hard to select some shapes to access their property grid in particular. After this changes, actual code permits to show the invisible shapes with a custom color and also show them as many levels as possible. The fixed do make that filtering to work again as it was before the refactor, the nodes that are over at the level 2 of depth of tree are collapsed, and the populate tree logic was moved out from the tree widget handling.