Windows Program Design Notes

1. When a child window sends a message to the parent window, the Child Window sends a wm_command message to the parent window.
Here, loword (wparam) is the subwindow ID, hiword (wparam) is the notification code, and lparam is the subwindow handle.
2. ID = getwindowlong (hwndchild, gwl_id); // obtain the ID
Id = getdlgctrlid (hwndchild); // same as above
Hwnd = getdlgitem (hwndparent, ID); // get handle 3. sendmessage (hwndbutton, bm_setstate,); // simulate the mouse to press the button message
Sendmessage (hwndbutton, bm_setstate,); // restore the mouse to normal
4. wparam of the wm_killfocus message is the window handle that accepts the input focus.
Wparam of the wm_setfocus message is the window handle that will soon lose the input focus
You can organize subwindows to obtain the input focus by processing the wm_killfocus message.
Case wm_killfocus:
If (hwnd = getparent (hwnd) wparam ))
Setfocus (hwnd );
Return 0;