Next links show how you could open snippet mode using GET parameters:

• http://localhost:8080/editor.html?snippetMode=true      - open snippet mode using default properties
• http://localhost:8080/editor.html?snippetMode=true&enablePageBorderLines=false&resizeCanvasOnZoom=true&
  resizeCanvasOnWindowResize=true&snippetModeViewOffsets.leftOffset=10&snippetModeViewOffsets.
  rightOffset=10&snippetModeViewOffsets.topOffset=10&snippetModeViewOffsets.pageOffset=10&
  snippetModeMargins.top=0.3&snippetModeMargins.bottom=0.3&snippetModeMargins.left=0.3&snippetModeMargins.right=0.3 - open snippet mode with overriding all default properties

Note: when you switched to snippet mode with custom properties, they will be remembered and when you switched on snippet mode once again they will be restored, so you do not need to provide them twice (for the same instance of the webRec).