The blocks, wires and groups on the canvas always snap to a grid. You can decide whether the grid is to be shown or not. The grid is not shown by default. When you zoom the canvas, the grid is zoomed accordingly.
To show or hide the grid
In the model editor, click the toolbar button for toggling the display of the grid.
When the grid is hidden, the button looks as follows: .
When the grid is shown, the button looks as follows: .
If the model is in the Active state (read-only mode), it is not possible to toggle the display of the grid and this button is therefore disabled.
To show or hide the grid
In the model editor, click the toolbar button for toggling the display of the grid. 
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