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Event to handle the drop.  Return true if you want the drop to continue, if you return false the element will move back where it started. This is a good place to save the position and size of the element.TODO look if it is true

onSelect

Every element that is selected will get this event, you can return true if you want the user to be able to select it, or false if you don't want that the users uses that element in clientDesign mode. It is better practice to set your element not selectable with the client design properties before you go into clientDesign mode because then the element is really not selectable and if you use this method you could see a second of selection. 

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