When you first open Paint, you are in Canvas
            mode. In Canvas mode, you can use brushes to modify your images.
            Brushes apply colour, filters, and Special Effects media to the
            image on the canvas. The brush cursor appears as a green cross surrounded
            by a circle when placed over the canvas. Canvas mode features are
            not available from multiple menus, such Canvas, Geometry, Fill,
            and Roll.
         
         You can also paint on
            the canvas using geometric shapes to define the path of the brush.
         
         To ease the painting
            of canvas edges, you can roll the canvas in the image window.
         
         To paint on the canvas:
         
         
            - Click Paint.
               The Paint menu appears.
                
- Click Canvas.
               If the scratch pad is
                  covering this button, swipe down to hide the scratch pad.
                
- From the Paint Mode controls, click Paint.
            
- Set a colour in the Current Colour pot.
               See 
                        Selecting Colours.
            
- Select a brush from the Brushes window.
               See 
                        Selecting a Brush.
            
- Set the brush attributes and modes in
               the Brush Attributes fields. See 
                        Brush Attributes and 
                        Brush Attribute Modes.
            
- Set the brush opacity in the Opacity
               field. Set the opacity to 100% to apply a fully opaque colour.
            
- Stroke the brush over the canvas. To
               paint straight horizontal and vertical lines, press Shift and drag the brush up and
               down or left and right.
            
- Click Undo (or press Ctrl+Z) to erase the strokes applied
               to the canvas since the last time you zoomed, panned, or changed
               a brush attribute.