(Execute the following example from within an MVC Project. For best results, you should use Squeak 3.7. MVC is seemingly broken in newer versions.) In the MVC display architecture, the basic display medium is a Form. This can be used as a source or destination for displaying on other Forms using a BitBlt object. The DisplayScreen "Display" is a kind of form, so you can draw directly on it like you can any other form:
| pen | pen := Pen newOnForm: Display. pen defaultNib: 4. 1 to: 50 do: [:i | pen go: i*4. pen turn: 89].will draw a black spiral in the center of the Display. Note that since you are drawing directly to the display, it draws over any existing views ("windows"), and will be erased as views are moved over it.
| form pen | form := Form extent: 300@300 depth: Display depth. form fillColor: How to lay out submorphs - example 2 green. pen := Pen newOnForm: form. pen defaultNib: 4. 1 to: 50 do: [:i | pen go: i*4. pen turn: 89]. form display. form displayAt: Display center - form center.Here the pen draws on the form, which in turn is then drawn on the Display at two locations. However, this is still drawing directly to the display, so it again draws over existing views and will be erased as views are moved over it.
| form pen view topView | form := Form extent: 300@300 depth: Display depth. form fillColor: Color green. pen := Pen newOnForm: form. pen defaultNib: 4. 1 to: 50 do: [:i | pen go: i*4. pen turn: 89]. view := FormView new. view model: form. view borderWidth: 2. topView := ColorSystemView new. topView model: form. "to set the correct window size" topView addSubView: view. topView controller open.Now the picture can be moved, resized, edited, etc.