In the process of developing WPF program, in the page of writing XAML, we can see that many default namespaces in the framework use a section of URL...

Copy these websites in the browser, not all of them can be directly accessed! How are these URLs defined and why can they be used to represent namespaces?

In the process of developing WPF program based on .NET Core 3, there is a need to encapsulate tool classes such as converter and formatter into another class library for reuse.

Therefore, after creating a new. Net core class library, copy the class file into it, and System.Windows.Data will be inaccessible when compiling!

It's strange that the new class library and the framework of the original WPF program are Microsoft.NETCore.App.

During the migration of. Net framework based projects to. Net core based projects, an error of ambiguousexception was thrown in the original project:

//Get the working area width of the screen
double x = SystemParameters.WorkArea.Width;
//Get screen working area height
double y = SystemParameters.WorkArea.Height;
//Get the overall screen width
double x1= SystemParameters.PrimaryScreenWidth;
//Get the overall height of the screen
double y1 = SystemParameters.PrimaryScreenHeight;

During the migration of WPF projects based on. Net framework to. Net core 3, system.windows.interactivity is no longer compatible.