Thread: Wndclassex And Wndclass

The differences stem from the difference between windows 3.0 and windows 3.1.
When windows 3.0 was released it only supported a few window styles. Over the years microsoft has decided to add to these and with the release of windows 3.1 they introduced the WNDCLASSEX struct and the RegisterClassEx() api function. The main difference is that this structure includes an extended style field. This gives you much more choice of the look and behaviour of your windows. At first with windows 3.1 there were only about 4 extended styles. Now there are lots more. Each new edition of windows seems to add something to the extended styles.

Most windows programmers say if you dont need extended styles then use WNDCLASS and RegisterClass() and if you do then use WNDCLASSEX and RegisterClassEx(). I say use WNDCLASSEX all the time and if you dont need extended styles set that field to 0. Best way of futureproofing your code.

from MSDN:

The WNDCLASSEX structure is similar to the WNDCLASS structure. There are two differences. WNDCLASSEX includes the cbSize member, which specifies the size of the structure, and the hIconSm member, which contains a handle to a small icon associated with the window class.

hope that helps

/btq