Fix changing column order in wxGrid when some columns are hidden.

Using negative column widths used for hidden columns when updating the column
positions after dragging one of them to a new position totally broke their
display. Fix this by ignoring the hidden columns.

Closes #16110.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@76452 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/generic/grid.cpp

@@ -4455,7 +4455,11 @@ void wxGrid::RefreshAfterColPosChange()
         {
             int colID = GetColAt( colPos );
 
-            colRight += m_colWidths[colID];
+            // Ignore the currently hidden columns.
+            const int width = m_colWidths[colID];
+            if ( width > 0 )
+                colRight += width;
+
             m_colRights[colID] = colRight;
         }
     }