Most widget sets/libraries implement the principle that it should be possible to cancel an action that you have started but not completed. For their checkboxes,

Most widget sets/libraries implement the principle that it should be possible to cancel an action that you have started but not completed. For their checkboxes, this would be pressing on the box but dragging the finger/pointer away from the checkbox and release elsewhere. With this "checkbox" 1) filling the entire screen, 2) activating on long press instead of displaying pressed state and activating on release, this is not possible. Also, a checkbox does not close the window/screen you are in. It may enable display/ungraying other widgets, but a checkbox itself does not navigate away: that is done by a secondary widget. Also, you could always uncheck a checkbox. Therefore, you could argue that this widget isn't actually a "checkbox" at all but just a widget that displays an image of one. It could just as well show a thumbs up or the text "Well done" to mean the same thing.