18. A non-transitory computer-readable storage medium storing program instructions, wherein the program instructions are computer-executable to implement: generating, in response to input, a digital sketch comprising one or more panels, one or more sketches each at least in part included in a respective one of the one or more panels, and one or more textual elements each included in a respective one of the panels, said generating the digital sketch comprising: generating the one or more panels according to panel input specifying a border for each of the one or more panels on a displayed page; generating the one or more sketches according to drawing input specifying one or more strokes on the page, wherein at least a portion of at least one of the one or more strokes is drawn in at least one of the one or more panels; erasing a portion of the border for at least one of the panels according to an erase input; determining for each of the one or more panels, based on a windowing algorithm, which of the one or more strokes or portions of the one or more strokes are to be displayed in the digital sketch and which of the one or more strokes or portions of the one or more strokes are hidden in the digital sketch, the windowing algorithm recognizing the erased portion of the border and said determining that the one or more strokes or portions of the strokes that pass through the erased portion of the border are to be displayed and the one or more strokes or portions of the strokes that do not pass through the erased portion of the border are to be hidden from display, and for a panel, the windowing algorithm performing: determining at least one of the strokes crosses the border of the panel; splitting each stroke that crosses the border of the panel to generate at least two separate strokes from the respective stroke; marking each stroke that lies inside the border of the panel to be displayed; determining at least one remaining unmarked stroke that intersects a marked stroke; and marking each remaining unmarked stroke that intersects a marked stroke as to be displayed and additional remaining unmarked strokes are hidden from display.
20. The non-transitory computer-readable storage medium as recited in claim 18 , wherein at least a portion of the panel input, the drawing input, and the erase input is received via touch or multitouch gestures applied to a touch-enabled or multitouch-enabled device.