Check the SOLID principle validity of the method DrawSelectionHint and its callees of the class ShapeDrawer.

Remove Dr.Smell for clarity, because it sucks. Dr.Smell was used only for submitting homework during the 2019 Fall Semester in Windows Programming course at National Taipei University of Technology.

On 4 January 2020, once the clear button is clicked to erase all shapes on the canvas, undo and redo behavior is undefined; that is, it looks buggy. As a result, the clear functionality should has its own ClearingCommand to fit with the undo redo mechanism.

Unlike DrawingForm.HandleCanvasMouseMoved and DrawingForm.HandleCanvasMouseReleased, DrawingForm.HandleCanvasMousePressed does not have to resize the mouse position to be inbound the canvas.

Update the GUI tests for undo, redo, and selecting shape.

On 4 January 2020, the shape drawing list represents the shape layer list. This constraints the application from expanding a new functionality to change the shapes' layer order.

On 4 January 2020, there are two identical code snippets for setting the currently selected shape info text in two versions of the view (one in DrawingForm.cs and one in DrawingPage.cs).
The logic for setting the currently selected shape info should be migrated to DrawingPresentationModel for better code quality and consistency.

On 4 January 2020, there are a total of five numbers representing the currently selected shape coordinates, which is weird.