WPF is all about Panels

Have you noticed how most applications' windows behave badly when it comes to adapt their dimensions to content or screen size? When you resize a window, only the center resizes and the other elements (toolbars, menus, ...) remain unchanged. Most popups have fixed size. It is true for local applications and also for HTML pages. HTML is supposed to be flexible and adapt its layout to content, but in real life, it is really difficult to control how HTML behaves. Apart from fixing elements' size, the result is unpredictable.

Fortunately today we have XAML, and the numerous Panels. Panels are in my opinion the most important contribution to complex application screens. But not every panel is equally useful. Forget about Canvas, which is the old fashioned way of placing element giving coordinates. It is all but flexible. Even the Grid panel that represents a table of cells is not as flexible as my favorite: the DockPanel. It fills up the window space starting from borders, and leaving the center for the main content. Be sure to fully understand how each kind of panel behaves, to be able to choose the correct one. Other useful panels are StackPanel, WrapPanel, ...

Panels come with another important notion: min/max width and height. Instead of fixing a column width, set its MinWidth value. It ensures that it will not render too thin if empty. Avoid at all cost fixing Width or Height, as you never know on what screen your application will be displayed. Test your interface with few or plenty of data, on tiny or huge screens. It should look great in every situation. Panels make it possible.