A div region that acts like a button. Single function - each button does one thing and always the same thing. Repeated clicks without intervening changes will have no additional effect.     sci_layout/button_div.html

Also buttons except uses canvas and not just a div. This version functions closer to a drop down menu in that the buttons are created as a set and correspond to a list of options of which only one can be active at a time.      sci_layout/button_canvas.html

A checkbox. Acts as a toggle to do and undo something.     sci_layout/checkbox.html

A drop down menu.     sci_layout/drop_down.html