All windows being positioned must have the same parent.

It is more efficient to use this function than to issue multiple WinSetWindowPos functions, as it causes less screen updating. If specifies a frame window, this function recalculates the sizes and positions of the frame controls. If the new window rectangle for any frame control is to be empty, instead of resizing or repositioning that control, it is hidden by (SWP_HIDE) instead. This eliminates needless processing of windows that are not visible. The window rectangle of the control in question is left in its original state. For example, if WinSetWindowPos is issued to change the size of a standard frame window to an empty rectangle, and WinQueryWindowRect is issued against the client window, the rectangle returned is not an empty rectangle, but the original client rectangle before WinSetWindowPos was issued.