The Old New Thing

With what operations is LockWindowUpdate not meant to be used?

February 22, 2007 Feb 22, 2007 02/22/07

Raymond Chen

Okay, now that we know what operations is meant to be used with, we can look at various ways people misuse the function for things unrelated to dragging. People see the "the window you lock won't be able to redraw itself" behavior of and use it as a sort of lazy version of the message. Though sending the message really isn't that much ...

With what operations is LockWindowUpdate meant to be used?

February 21, 2007 Feb 21, 2007 02/21/07

Raymond Chen

As I noted earlier, the intended purpose of can be captured in one word: dragging. The simplest case of is used by the window manager when you move or resize a window and "Show window contents while dragging" is disabled. When you start the move/size operation, the window manager locks the entire desktop so it can draw the dotted-rectangle...

How is LockWindowUpdate meant to be used?

February 20, 2007 Feb 20, 2007 02/20/07

Raymond Chen

Now that we know how works, we can look at what it is for. Actually, the intended purpose of can be captured in one word: dragging. But we'll get to that a little later. The purpose of is to allow a program to temporarily take over the responsibility of drawing a window. Of course, in order to do this, you have to prevent the window ...

What does LockWindowUpdate do?

February 19, 2007 Feb 19, 2007 02/19/07

Raymond Chen

Poor misunderstood . This is the first in a series on , what it does, what it's for and (perhaps most important) what it's not for. What does is pretty simple. When a window is locked, all attempt to draw into it or its children fail. Instead of drawing, the window manager remembers which parts of the window the application tried to draw...

Why don't I use any class libraries in my sample code?

February 16, 2007 Feb 16, 2007 02/16/07

Raymond Chen

As a general rule, I avoid using any class libraries in my sample code. This isn't because I'm opposed to class libraries, but rather because I don't want to narrow my audience to "people who use MFC" (to choose one popular class library). If I were to start using MFC for all of my samples, I'd probably lose all the people who don't use MFC...