Panel. These Panel elements enable many complex layouts. For example, stacking elements can easily be achieved by using the StackPanel element, while more complex and free flowing layouts are possible by using a Canvas.Panel controls:PanelPanelCanvasDockPanelGridRelativePanelStackPanelWrapPanelPanel is an abstract class and laying out multiple controls to fill the available space is usually done with a Grid with no rows/columns. In Avalonia Panel is a usable control that has the same layout behavior as a Grid with no rows/columns, but with a lighter runtime footprint.Control consumed by the layout system can be thought of as a rectangle that is slotted into the layout. The Bounds property returns the boundaries of an element's layout allocation. The size of the rectangle is determined by calculating the available screen space, the size of any constraints, layout-specific properties (such as margin and padding), and the individual behavior of the parent Panel element. Processing this data, the layout system is able to calculate the position of all the children of a particular Panel. It is important to remember that sizing characteristics defined on the parent element, such as a Border, affect its children.Panel element's Children collection. Layout is an intensive process. The larger the Children collection, the greater the number of calculations that must be made. Complexity can also be introduced based on the layout behavior defined by the Panel element that owns the collection. A relatively simple Panel, such as Canvas, can have significantly better performance than a more complex Panel, such as Grid.Control are evaluated, such as Width, Height, and Margin.Panel-specific logic is applied, such as Dock direction or stacking Orientation.Children collection is drawn on the screen.Children are added to the collectionChildren collection, a measure pass and an arrange pass. Each child Panel provides its own MeasureOverride and ArrangeOverride methods to achieve its own specific layout behavior.Children collection is evaluated. The process begins with a call to the Measure method. This method is called within the implementation of the parent Panel element, and does not have to be called explicitly for layout to occur.Visual such as Clip and IsVisible are evaluated. This generates a constraint that is passed to MeasureCore.Control, such as its Height, Width and Margin. Each of these properties can change the space that is necessary to display the element. MeasureOverride is then called with the constraint as a parameter.Bounds is a calculated value, you should be aware that there could be multiple or incremental reported changes to it as a result of various operations by the layout system. The layout system may be calculating required measure space for child elements, constraints by the parent element, and so on.DesiredSize, which occurs during the MeasureCore call. The DesiredSize value is stored by Measure for use during the content arrange pass.Arrange method. During the arrange pass, the parent Panel element generates a rectangle that represents the bounds of the child. This value is passed to the ArrangeCore method for processing.ArrangeCore method evaluates the DesiredSize of the child and evaluates any additional margins that may affect the rendered size of the element. ArrangeCore generates an arrange size, which is passed to the ArrangeOverride method of the Panel as a parameter. ArrangeOverride generates the finalSize of the child. Finally, the ArrangeCore method does a final evaluation of offset properties, such as margin and alignment, and puts the child within its layout slot. The child does not have to (and frequently does not) fill the entire allocated space. Control is then returned to the parent Panel and the layout process is complete.