new_contents: import unreal_engine as ue
  from unreal_engine import FSlateIcon, FSlateStyleSet, FLinearColor
  from unreal_engine.structs import SlateBrush, SlateColor, Vector2D
  
  # this code must be in ue_site.py, extenders must be  registered during editor startup phase !!!
  
  # we create a new StyleSet to register a new Icon
  
  # create a new styleset
  style = FSlateStyleSet('PyStyle')
  # allocate a solid color brush (check here https://docs.unrealengine.com/latest/INT/API/Runtime/SlateCore/Styling/FSlateBrush/index.html)
  brush = SlateBrush(TintColor=SlateColor(SpecifiedColor=FLinearColor(1, 0, 0, 1)))
  # register the brush in the 'PyStyle' StyleSet
  style.set('SolidBrush001', brush)
  # allocate a brush image (best image size for toolbar is 64x64)
  # Note: pass a path to a valid image file
  brush2 = SlateBrush(ResourceName='C:/Users/Roberto/Desktop/chessboard.png', ImageSize=Vector2D(X=128, Y=128))
  # register the brush
  style.set('ImageBrush001', brush2)
  # register the new style
  style.register()
  
  # this is called whenever you select the SimpleMenuExtension entry
  def dumb():
     ue.log('HELLO WORLD')
  
  # this generates the menu entries
  def open_menu(menu):
     menu.begin_section('test1', 'test2')
     menu.add_menu_entry('one', 'two', lambda: ue.log('ciao 1'))
     menu.add_menu_entry('three', 'four', lambda: ue.log('ciao 2'))
     menu.end_section()
  
  # this fills the toolbar
  def fill_toolbar(toolbar):
  	icon1 = FSlateIcon('PyStyle', 'SolidBrush001')
  	icon2 = FSlateIcon('PyStyle', 'ImageBrush001')
  	toolbar.add_tool_bar_button('button001', 'Button001', 'Button001 tooltip', icon1, lambda: ue.log('Button001'))
  	toolbar.add_tool_bar_button('button002', 'Button002', 'Button002 tooltip', icon2, lambda: ue.log('Button002'))
  
  ue.add_menu_extension('SimpleMenuExtension', dumb)
  
  ue.add_menu_bar_extension('SimpleMenuBarExtension', open_menu)
  
  ue.add_tool_bar_extension('SimpleToolBarExtension', fill_toolbar)
  
subject: Create extenders_example.py