How to stop Explorer starting my application maximized?

Question

Explorer seems to always start my application with SW_MAXIMIZE (STARTF_USESHOWWINDOW is set in STARTUPINFO.dwFlags). I know that ShowWindow

Answer 1

My first thought was to turn off STARTF_USESHOWWINDOW in the PEB if the parent wanted me to start maximized but that is too nasty and undocumented so I have not tried that yet.

---

Preventing any kind of size change (which is OK for my application since it is just a "modal" dialog) sort of works:

case WM_WINDOWPOSCHANGING:
  ((WINDOWPOS*)lp)->flags |= SWP_NOSIZE;
  return true;

The problem is that the window position is still set to 0 x 0 like a maximized window.

---

A better solution seems to be to detect and correct the problem after WM_INITDIALOG:

case WM_INITDIALOG:
  PostMessage(hDlg, WM_APP, 0, 0);
  break;
case WM_APP:
  if (IsZoomed(hDlg)) ShowWindow(hDlg, SW_SHOWNOACTIVATE);
  break;