* Add ui.Window to easily create reusable windows with titles.
* Add a palette window (panel) to the right edge of the Edit Mode.
* Has Radio Buttons listing the colors available in the palette.
* Add palette support to Edit Mode so when you draw pixels, they take
on the color and attributes of the currently selected Swatch in your
palette.
* Revise the on-disk format to better serialize the Palette object to
JSON.
* Break Play Mode: collision detection fails because the Grid key
elements are now full Pixel objects (which retain their Palette and
Swatch properties).
* The Grid will need to be re-worked to separate X,Y coordinates from
the Pixel metadata to just test "is something there, and what is
it?"
CheckButton is a generic component based on Button that additionally
takes a *bool variable to manage. When the CheckButton is clicked or
unclicked, it will toggle the bool var and its border style will "stick"
in or out depending on the state.
Checkbox is a Frame widget that wraps a CheckButton and another child
widget, such as a Label. Interacting with the child widget will forward
all of its mouse events to the CheckButton, so that the Label could be
clicked instead of just the box itself.
Noah