Some minor corrections (typos, return value handling).

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@36633 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/os2/dialog.cpp

@@ -266,7 +266,7 @@ bool wxDialog::Show( bool bShow )
     if ( bShow )
     {
         // dialogs don't get WM_SIZE message after creation unlike most (all?)
-        // other windows and so could start their life non laid out correctly
+        // other windows and so could start their life not laid out correctly
         // if we didn't call Layout() from here
         //
         // NB: normally we should call it just the first time but doing it

src/os2/slider.cpp

@@ -812,8 +812,10 @@ void wxSlider::GetPosition(
         vPoint.x -= vPt.x;
         vPoint.y -= vPt.y;
     }
-    *pnX = vPoint.x;
-    *pnY = vPoint.y;
+    if (pnX)
+        *pnX = vPoint.x;
+    if (pnY)
+        *pnY = vPoint.y;
 } // end of wxSlider::GetPosition
 
 int wxSlider::GetSelEnd() const

src/os2/spinctrl.cpp

@@ -1,6 +1,6 @@
 /////////////////////////////////////////////////////////////////////////////
-// Name:        msw/spinctrl.cpp
-// Purpose:     wxSpinCtrl class implementation for Win32
+// Name:        os2/spinctrl.cpp
+// Purpose:     wxSpinCtrl class implementation for OS/2
 // Author:      David Webster
 // Modified by:
 // Created:     10/15/99

src/os2/utilsgui.cpp

@@ -428,8 +428,10 @@ void wxDisplaySize(
         ::DevCloseDC(hdcScreen);
         ::WinReleasePS(hpsScreen);
     }
-    *pWidth = (int)lWidth;
-    *pHeight = (int)lHeight;
+    if (pWidth)
+        *pWidth = (int)lWidth;
+    if (pHeight)
+        *pHeight = (int)lHeight;
 }
 
 void wxDisplaySizeMM(