Reconstructing the Screen

On a character-based system, during program execution when a control is resized, moved, hidden, or removed (destroyed), the runtime system applies the following procedure to reconstruct and display the screen:

  1. The screen is reconstructed in memory, in a virtual screen, before being displayed to the physical screen.
  2. The portion of the screen underneath the affected control is redrawn to the virtual screen with the attributes and colors of the owning window (this usually results in that area of the screen being filled with the owning window's background color).
  3. Any controls that overlap the affected area are redrawn in the order in which they were originally created.
  4. The changed portions of the screen (constructed in memory) are displayed to the physical screen.