[Bug 22369] A child window without WS_EX_MDICHILD style should not be tiled by the WM_MDITILE message.

http://bugs.winehq.org/show_bug.cgi?id=22369

--- Comment #12 from [e-mail]  2010-04-17 06:33:00 ---
In MS Windows, All MDI child windows must be created with the WS_EX_MDICHILD
style.

The CreateMDIWindow API and the WM_MDICREATE message set that style on the
child window automatically.

(The application can use the CreateWindowEx API with the WS_EX_MDICHILD style
to create MDI child windows.)

So, if a child window of an MDI client(parent) window is not with the
WS_EX_MDICHILD style, it is not considered as an MDI child window.

Do you understand?