Detect the use of incompatible flags for wxGridSizer too.

Complain if wxEXPAND is combined with both horizontal and vertical alignment
flags, as this doesn't make sense and, moreover, the behaviour has changed
since the last commit: now wxEXPAND is ignored instead of overriding the
alignment flags if they are combined.

src/common/sizer.cpp

@@ -1406,6 +1406,18 @@ wxSizerItem *wxGridSizer::DoInsert(size_t index, wxSizerItem *item)
         }
     }
 
+    const int flags = item->GetFlag();
+    if ( flags & wxEXPAND )
+    {
+        // Check that expansion will happen in at least one of the directions.
+        wxASSERT_MSG
+        (
+            !(flags & (wxALIGN_BOTTOM | wxALIGN_CENTRE_VERTICAL)) ||
+                !(flags & (wxALIGN_RIGHT | wxALIGN_CENTRE_HORIZONTAL)),
+            wxS("wxEXPAND flag will be overridden by alignment flags")
+        );
+    }
+
     return wxSizer::DoInsert(index, item);
 }