From Xojo Documentation
A Rectangle control draws a rectangle that can be of any length, width, border color, and fill color. By default, rectangles are 100 pixels in length and width, with a black border that is 1 pixel thick and a white center. You can style the Rectangle by applying a Style.
For example, by applying a Style with all the Corner Radii set to 25px you can create a rounded rectangle.
Left, Top, Width, Height
- These values change the position and size of the rectangle.
- Applies a Style to the Rectangle to change its appearance.
Generally you configure a Rectangle in the Inspector. However you can also change Rectangle properties, such as its Left, Top, Width, Height and Style in code.
For example if you have a Style called CornerStyle you can set it in code like this: