Fix the client area changing size on Windows when restoring a window.

This was caused by WM_SYSCOMMAND handler not properly setting the extended style. Now, it respects it correctly. It's not obvious why we need to do this in the first place, but the comment around the code suggests that it's related to display constraints.

Fixes #1433

Author: SiegeLord

src/win/wwindow.c

@@ -739,6 +739,8 @@ static LRESULT CALLBACK window_callback(HWND hWnd, UINT message,
          break;
       }
       case WM_SYSCOMMAND: {
+         DWORD style;
+         DWORD exstyle;
          if (_al_win_disable_screensaver &&
                ((wParam & 0xfff0) == SC_MONITORPOWER || (wParam & 0xfff0) == SC_SCREENSAVE)) {
             return 0;
@@ -751,11 +753,13 @@ static LRESULT CALLBACK window_callback(HWND hWnd, UINT message,
          /* This is used by WM_GETMINMAXINFO to set constraints. */
          else if ((wParam & 0xfff0) == SC_MAXIMIZE) {
             d->flags |= ALLEGRO_MAXIMIZED;
-            SetWindowLong(hWnd, GWL_EXSTYLE, WS_EX_APPWINDOW);
+            display_flags_to_window_styles(d->flags, &style, &exstyle);
+            SetWindowLong(hWnd, GWL_EXSTYLE, exstyle);
          }
          else if ((wParam & 0xfff0) == SC_RESTORE) {
             d->flags &= ~ALLEGRO_MAXIMIZED;
-            SetWindowLong(hWnd, GWL_EXSTYLE, WS_EX_APPWINDOW | WS_EX_OVERLAPPEDWINDOW);
+            display_flags_to_window_styles(d->flags, &style, &exstyle);
+            SetWindowLong(hWnd, GWL_EXSTYLE, exstyle);
          }
          break;
       }