Fix resizing of wxGrid columns when they were reordered.

The column resizing code in wxGrid didn't take account of the fact that the
column positions and indices could be different. Correct it by inserting calls
to wxGrid::GetColAt() and GetColPos() in a new wxGridOperations::GetLineBefore()
method.

Closes #11984.

git-svn-id: https://svn.wxwidgets.org/svn/wx/wxWidgets/trunk@66137 c3d73ce0-8a6f-49c7-b76d-6d57e0e08775

src/generic/grid.cpp

@@ -6281,7 +6281,9 @@ int wxGrid::PosToEdgeOfLine(int pos, const wxGridOperations& oper) const
         else if ( line > 0 &&
                     pos - oper.GetLineStartPos(this,
                                                line) < WXGRID_LABEL_EDGE_ZONE )
-            return line - 1;
+        {
+            return oper.GetLineBefore(this, line);
+        }
     }
 
     return -1;