 Sample image
The task is to demonstrate the creation of a series of vertical pinstripes across the entire width of the display.

 in the first quarter the pinstripes should alternate one pixel white, one pixel black = 1 pixel wide vertical pinestripes
 Quarter of the way down the display, we can switch to a wider 2 pixel wide vertical pinstripe pattern, alternating two pixels white, two pixels black. 
 Half way down the display, we switch to 3 pixels wide, 
 for the lower quarter of the display we use 4 pixels.


c.f. Colour_pinstripe/Display

package require Tcl 8.5
package require Tk 8.5
 
wm attributes . -fullscreen 1
pack [canvas .c -highlightthick 0] -fill both -expand 1
set colors {black white}
 
set dy [expr {[winfo screenheight .c]/4}]
set y 0
foreach dx {1 2 3 4} {
    for {set x 0} {$x < [winfo screenwidth .c]} {incr x $dx} {
	.c create rectangle $x $y [expr {$x+$dx}] [expr {$y+$dy}] \
            -fill [lindex $colors 0] -outline {}
	set colors [list {*}[lrange $colors 1 end] [lindex $colors 0]]
    }
    incr y $dy
}