TreeView
  - Name editing
     - Detect mouse input in TreeView and if I double click over a GUILabel start rename
     - Or if I select it and hit F2 also start rename
     - Has callbacks with which it notifies TreeView of actual changes
  - Selecting
     - Clicking on a row of TreeView sets a flag that item is selected, and a GUIElement is created. 
     - Element is positioned in updateLayoutInternal and it shows a different colored background
  - Deleting
      - Simply track currently selected element and Delete event

Implementation steps:
 - Selection
   - Clicking on element selects it, delete removes it, F2 renames is. Slow double click renames it.
   - Rename implementation to follow, just set up an empty method for now
   - Callback on selection
 - Rename implementation
   - When rename is initiated hide the objects label and replace it with an input-box with the same text as a label
   - Rename ends when user hits enter or click anywhere else but the rename box
 - Drag and drop
   - If a mouse drag is detected DragAndDropManager is activated
   - Element is not removed from its original position until drag is complete
   - Dragging over an element will make a highlight box appear around it
   - Dragging between elements will make a thick line appear between them
   - Releasing the drag changes the element parents
 - Auto scroll
    - Sliding over top or bottom of the tree view while dragging an element will search GUIElement parents to find a ScrollArea. If it finds one it will attempt to scroll up or down.

Detecting external clicks:
 - LostFocus event?
   - Triggered when I click on another control within my own windows, or when controls parent window loses the focus himself
   - Each GUIElement can implement acceptsMouseFocus event. If it does, then mouse click will cause a ReceivedFocus event.
     - Mouse click on any other element, or window losing focus will trigger LostFocus events
 - I can replace clumsy Selective Input with this approach
 - DropDownBox can also use the same approach although I will likely need to convert DropDownBox to a GUIElement - DO THIS AFTER TreeView implementation is working