user32: Fix initial computation of client area in WM_NCCALCSIZE for RTL windows.

dlls/user32/controls.h

@@ -167,7 +167,7 @@ extern void MENU_EndMenu(HWND) DECLSPEC_HIDDEN;
 /* nonclient area */
 extern LRESULT NC_HandleNCPaint( HWND hwnd , HRGN clip) DECLSPEC_HIDDEN;
 extern LRESULT NC_HandleNCActivate( HWND hwnd, WPARAM wParam, LPARAM lParam ) DECLSPEC_HIDDEN;
-extern LRESULT NC_HandleNCCalcSize( HWND hwnd, RECT *winRect ) DECLSPEC_HIDDEN;
+extern LRESULT NC_HandleNCCalcSize( HWND hwnd, WPARAM wParam, RECT *winRect ) DECLSPEC_HIDDEN;
 extern LRESULT NC_HandleNCHitTest( HWND hwnd, POINT pt ) DECLSPEC_HIDDEN;
 extern LRESULT NC_HandleNCLButtonDown( HWND hwnd, WPARAM wParam, LPARAM lParam ) DECLSPEC_HIDDEN;
 extern LRESULT NC_HandleNCLButtonDblClk( HWND hwnd, WPARAM wParam, LPARAM lParam) DECLSPEC_HIDDEN;

dlls/user32/defwnd.c

@@ -309,7 +309,7 @@ static LRESULT DEFWND_DefWinProc( HWND hwnd, UINT msg, WPARAM wParam, LPARAM lPa
         }
 
     case WM_NCCALCSIZE:
-        return NC_HandleNCCalcSize( hwnd, (RECT *)lParam );
+        return NC_HandleNCCalcSize( hwnd, wParam, (RECT *)lParam );
 
     case WM_WINDOWPOSCHANGING:
         return WINPOS_HandleWindowPosChanging( hwnd, (WINDOWPOS *)lParam );

dlls/user32/nonclient.c

@@ -410,7 +410,7 @@ BOOL WINAPI AdjustWindowRectEx( LPRECT rect, DWORD style, BOOL menu, DWORD exSty
  *
  * Handle a WM_NCCALCSIZE message. Called from DefWindowProc().
  */
-LRESULT NC_HandleNCCalcSize( HWND hwnd, RECT *winRect )
+LRESULT NC_HandleNCCalcSize( HWND hwnd, WPARAM wparam, RECT *winRect )
 {
     RECT tmpRect = { 0, 0, 0, 0 };
     LRESULT result = 0;
@@ -451,7 +451,11 @@ LRESULT NC_HandleNCCalcSize( HWND hwnd, RECT *winRect )
                         - GetSystemMetrics(SM_CYEDGE));
 
         if (style & WS_VSCROLL)
-            if( winRect->right - winRect->left >= GetSystemMetrics(SM_CXVSCROLL)){
+            if (winRect->right - winRect->left >= GetSystemMetrics(SM_CXVSCROLL))
+            {
+                /* rectangle is in screen coords when wparam is false */
+                if (!wparam && (exStyle & WS_EX_LAYOUTRTL)) exStyle ^= WS_EX_LEFTSCROLLBAR;
+
                 if((exStyle & WS_EX_LEFTSCROLLBAR) != 0)
                     winRect->left  += GetSystemMetrics(SM_CXVSCROLL);
                 else