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docs/ItemContainer-Overview.md

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+The ```ItemContainer``` is the **most important** piece of an editor. It is a content control that wraps every other control that is generated by the ```NodifyEditor```'s ```ItemsSource``` and has a `Location` in graph coordinates. 
+
+## Table of contents
+ - [Selecting](#selecting)
+   - [API](#selection-api)
+ - [Moving](#moving-and-dragging)
+
+## Selecting
+
+Selecting an ```ItemContainer``` is done by releasing the left mouse button over the bounding box of the container. The bounding box is calculated using the ```DesiredSizeForSelection``` dependency property if specified, otherwise using the ```RenderSize```. 
+
+> Note: A container can be selected programmatically by setting the ```IsSelected``` dependency property to ```true```.
+
+The container will also be selected if the left mouse button is not released and the mouse is moved, which will clear the current selection and start a dragging operation on the selected container.
+
+Selection can also be done by releasing the right mouse button on the container which will clear the current selection and select the target container.
+
+Different behavior is used depending on the ```ModifierKeys``` held when selecting a container:
+- ```Replace``` - no modifier key (default behavior, clears the selected items and selects the container)
+- ```Append``` - shift key (adds the container to the selected items)
+- ```Invert``` - control key (toggles the container's ```IsSelected``` dependency property)
+
+An ```ItemContainer``` can only be selected if the ```IsSelectable``` dependency property is ```true```.
+
+Selecting or unselecting a container will fire the ```Selected``` event, respectively the ```Unselected``` event, and will set the ```IsSelected``` dependency property to the new value.
+
+If the default style is not overridden, the container's border will use the ```SelectedBrush``` dependency property.
+
+Default values:
+- ```IsSelectable```: true
+- ```IsSelected```: false
+
+### Selection API
+
+* IsSelectableInArea
+
+## Moving and dragging
+
+A dragging operation can be started by holding the left mouse button on an ```ItemContainer``` and moving the mouse.
+An ```ItemContainer``` can be dragged only if its ```IsDraggable``` dependency property is set to ```true```.
+
+> Note: ```ItemContainer```s can be programmatically moved by setting their ```Location``` dependency property.
+
+Dragging an ```ItemContainer``` fires a sequence of events that are handled by the ```NodifyEditor``` and applies to all the selected items:
+- ```DragStarted``` - will set ```IsPreviewingLocation``` dependency property to ```true```;
+- ```DragDelta``` - will be fired until the dragging operation is finished or canceled and will move all the selected items with it;
+- ```DragCompleted``` - will finish or cancel the dragging operation and set the ```Location``` dependency property to the final position and ```IsPreviewingLocation``` to ```false```.
+
+> Note: A dragging operation can be canceled by releasing the right mouse button if ```AllowDraggingCancellation``` is set to ```true```.
+
+Default values:
+- ```IsDraggable```: true
+- ```AllowDraggingCancellation```: true