diff --git a/rtl/win16/win31.pp b/rtl/win16/win31.pp
index 048323b314..74caa010a5 100644
--- a/rtl/win16/win31.pp
+++ b/rtl/win16/win31.pp
@@ -515,6 +515,42 @@ const
   WS_EX_ACCEPTFILES = $00000010;
   WS_EX_TRANSPARENT = $00000020;
 
+type
+{ Window size, position, Z-order, and visibility }
+  PWINDOWPLACEMENT = ^WINDOWPLACEMENT;
+  LPWINDOWPLACEMENT = ^WINDOWPLACEMENT; far;
+  WINDOWPLACEMENT = record
+    length: UINT;
+    flags: UINT;
+    showCmd: UINT;
+    ptMinPosition: POINT;
+    ptMaxPosition: POINT;
+    rcNormalPosition: RECT;
+  end;
+  TWindowPlacement = WINDOWPLACEMENT;
+
+const
+  WPF_SETMINPOSITION     = $0001;
+  WPF_RESTORETOMAXIMIZED = $0002;
+
+  WM_WINDOWPOSCHANGING   = $0046;
+  WM_WINDOWPOSCHANGED    = $0047;
+
+type
+{ WM_WINDOWPOSCHANGING/CHANGED struct pointed to by lParam }
+  PWINDOWPOS = ^WINDOWPOS;
+  LPWINDOWPOS = ^WINDOWPOS; far;
+  WINDOWPOS = record
+    hwnd: HWND;
+    hwndInsertAfter: HWND;
+    x: SmallInt;
+    y: SmallInt;
+    cx: SmallInt;
+    cy: SmallInt;
+    flags: UINT;
+  end;
+  TWindowPos = WINDOWPOS;
+
 function GetFreeSystemResources(SysResource: UINT): UINT; external 'USER';
 
 procedure LogError(err: UINT; lpInfo: FarPointer); external 'KERNEL';
@@ -666,6 +702,10 @@ function RegisterClass(lpwc: LPWNDCLASS): ATOM; external 'USER';
 function RegisterClass(var wc: WNDCLASS): ATOM; external 'USER';
 {$endif}
 
+{ Window size, position, Z-order, and visibility }
+function GetWindowPlacement(hwnd: HWND; lpwndpl: LPWINDOWPLACEMENT): BOOL; external 'USER';
+function SetWindowPlacement(hwnd: HWND; lpwndpl: LPWINDOWPLACEMENT): BOOL; external 'USER';
+
 implementation
 
 end.
diff --git a/rtl/win16/winprocsh.inc b/rtl/win16/winprocsh.inc
index aee0ff1280..f8dfed8557 100644
--- a/rtl/win16/winprocsh.inc
+++ b/rtl/win16/winprocsh.inc
@@ -848,3 +848,21 @@ function GetWindowWord(hwnd: HWND; nOffset: SmallInt): WORD; external 'USER';
 function SetWindowWord(hwnd: HWND; nOffset: SmallInt; nVal: WORD): WORD; external 'USER';
 function GetWindowLong(hwnd: HWND; nOffset: SmallInt): LONG; external 'USER';
 function SetWindowLong(hwnd: HWND; nOffset: SmallInt; nVal: LONG): LONG; external 'USER';
+
+{ Window size, position, Z-order, and visibility }
+
+procedure GetClientRect(hwnd: HWND; lprc: LPRECT); external 'USER';
+procedure GetWindowRect(hwnd: HWND; lprc: LPRECT); external 'USER';
+{$ifdef VAR_PARAMS_ARE_FAR}
+procedure GetClientRect(hwnd: HWND; var rc: RECT); external 'USER';
+procedure GetWindowRect(hwnd: HWND; var rc: RECT); external 'USER';
+{$endif}
+
+function SetWindowPos(hwnd, hwndInsertAfter: HWND; x, y, cx, cy: SmallInt; fuFlags: UINT): BOOL; external 'USER';
+
+function BeginDeferWindowPos(cWindows: SmallInt): HDWP; external 'USER';
+function DeferWindowPos(hdwp: HDWP; hwnd, hwndInsertAfter: HWND; x, y, cx, cy: SmallInt; flags: UINT): HDWP; external 'USER';
+function EndDeferWindowPos(hdwp: HDWP): BOOL; external 'USER';
+
+function MoveWindow(hwnd: HWND; nLeft, nTop, nWidth, nHeight: SmallInt; fRepaint: BOOL): BOOL; external 'USER';
+function BringWindowToTop(hwnd: HWND): BOOL; external 'USER';
diff --git a/rtl/win16/wintypes.inc b/rtl/win16/wintypes.inc
index d8ca83529a..4b3b238922 100644
--- a/rtl/win16/wintypes.inc
+++ b/rtl/win16/wintypes.inc
@@ -1547,3 +1547,52 @@ const
   GWW_ID              = (-12);
   GWL_STYLE           = (-16);
   GWL_EXSTYLE         = (-20);
+
+{ Window size, position, Z-order, and visibility }
+
+  CW_USEDEFAULT      = SmallInt($8000);
+
+{ SetWindowPos() and WINDOWPOS flags }
+  SWP_NOSIZE         = $0001;
+  SWP_NOMOVE         = $0002;
+  SWP_NOZORDER       = $0004;
+  SWP_NOREDRAW       = $0008;
+  SWP_NOACTIVATE     = $0010;
+  SWP_FRAMECHANGED   = $0020;  { The frame changed: send WM_NCCALCSIZE }
+  SWP_SHOWWINDOW     = $0040;
+  SWP_HIDEWINDOW     = $0080;
+  SWP_NOCOPYBITS     = $0100;
+  SWP_NOOWNERZORDER  = $0200;  { Don't do owner Z ordering }
+
+  SWP_DRAWFRAME      = SWP_FRAMECHANGED;
+  SWP_NOREPOSITION   = SWP_NOOWNERZORDER;
+
+  SWP_NOSENDCHANGING = $0400;
+  SWP_DEFERERASE     = $2000;
+
+{ SetWindowPos() hwndInsertAfter field values }
+  HWND_TOP           = HWND(0);
+  HWND_BOTTOM        = HWND(1);
+  HWND_TOPMOST       = HWND(-1);
+  HWND_NOTOPMOST     = HWND(-2);
+
+type
+  HDWP = THandle;
+
+const
+  WM_MOVE            = $0003;
+  WM_SIZE            = $0005;
+
+{ WM_SIZE message wParam values }
+  SIZE_RESTORED      = 0;
+  SIZE_MINIMIZED     = 1;
+  SIZE_MAXIMIZED     = 2;
+  SIZE_MAXSHOW       = 3;
+  SIZE_MAXHIDE       = 4;
+
+{ Obsolete constant names }
+  SIZENORMAL         = SIZE_RESTORED;
+  SIZEICONIC         = SIZE_MINIMIZED;
+  SIZEFULLSCREEN     = SIZE_MAXIMIZED;
+  SIZEZOOMSHOW       = SIZE_MAXSHOW;
+  SIZEZOOMHIDE       = SIZE_MAXHIDE;