Why is the thread blocking so strangely?

Question

WPF

Faced a problem. The stream somehow strangely is blocked. The code is like this:

LambdaMechanism Mech = new LambdaMechanism(Angle, Radius);
Mech.Draw(canvas);
Thread.Sleep(TimeSpan.FromSeconds(3));
MessageBox.Show("Yes");

According to my logic, this code should draw the necessary elements, and then after 3 seconds display Yes on the screen. But in fact, after starting, after 3 seconds, elements are drawn at the same time and Yes is displayed on the screen. What is the problem? Inside Mech.Draw(), threads, timers, etc. are not affected.
PS I know that you can do this:

Task.Delay(3000).ContinueWith(_ => MessageBox.Show("Yes"))

But that option doesn't work for me. It is necessary to "stop" the execution of the code for 3 seconds

Answer 1

You are putting UIThread to sleep.
And you can't do that.
You will have to create a new thread and stop it for 3 seconds, then output Yes.

LambdaMechanism Mech = new LambdaMechanism(Angle, Radius);
Mech.Draw(canvas);
new Thread(()=> 
{
Thread.Sleep(TimeSpan.FromSeconds(3));
MessageBox.Show("Yes");
}).Start();

As an option.
So or:
It seems that the
Graphics thread does not draw elements instantly.
And you put him to sleep, and of course he does not have time to draw what you need.