code: function setViews(v) {
              // setting to 0 prevents exception when on/off view is not defined
              this.viewSizes.expandedToggle  = { width: 0, height : 0};
              this.viewSizes.collapsedToggle = { width: 0, height : 0};
              this.viewSizes.expandedSign    = { width: 0, height : 0};
              this.viewSizes.collapsedSign   = { width: 0, height : 0};
              this.viewSizes.leafSign        = { width: 0, height : 0};
  
              for(var k in v) {
                  this.views[k] = zebkit.draw.$view(v[k]);
                  if (this.viewSizes.hasOwnProperty(k) && this.views[k]) {
                      this.viewSizes[k] = this.views[k].getPreferredSize();
                  }
              }
  
              this.vrp();
              return this;
          }
docs: Set the number of views to customize rendering of different visual elements of the tree
  UI component. The following decorative elements can be customized:
  
  - **"collapsedSign"** - closed tree item icon view
  - **"expandedSign"**  - opened tree item icon view
  - **"leafSign"**  - leaf tree item icon view
  - **"expandedToggle"**    - toggle on view
  - **"collapsedToggle"**   - toggle off view
  - **"focusOffSelect"**   - a view to express an item selection when tree component doesn't hold focus
  - **"focusOnSelect"**   - a view to express an item selection when tree component holds focus
  
  For instance:
  
  build tree UI component
  var tree = new zebkit.ui.tree.Tree({
  value: "Root",
  kids: [
  "Item 1",
  "Item 2"
  ]
  });
  
  set " [x] " text render for toggle on and
  " [o] " text render for toggle off tree elements
  tree.setViews({
  "expandedToggle" : new zebkit.draw.TextRender(" [x] "),
  "collapsedToggle": new zebkit.draw.TextRender(" [o] ")
  });
  
  @param {Object} v dictionary of tree component decorative elements views
  @method setViews
  @chainable