Fix rendering of owner-drawn multi-column menus in wxMSW

Compute the item rectangle bounds correctly for the items in non-first column.

See #17072.

(cherry picked from commit 61083f4871)

docs/changes.txt

@@ -629,6 +629,7 @@ wxGTK:
 wxMSW:
 
 - Fix compilation with g++ 4.9 in non-C++11 mode.
+- Fix rendering of owner drawn multi-column menus (Pete Bannister).
 - Fix regression in accessibility support (Leland Lucius).
 - Fix regression in wxDC drawing with bottom-to-top y axis (Artur Wieczorek).
 - Fix compilation with C++Builder XE compiler (Nichka).

src/msw/menuitem.cpp

@@ -873,7 +873,8 @@ bool wxMenuItem::OnDrawItem(wxDC& dc, const wxRect& rc,
         data->SeparatorMargin.ApplyTo(rcSeparator);
 
         RECT rcGutter = rcSelection;
-        rcGutter.right = data->ItemMargin.cxLeftWidth
+        rcGutter.right = rcGutter.left
+                       + data->ItemMargin.cxLeftWidth
                        + data->CheckBgMargin.cxLeftWidth
                        + data->CheckMargin.cxLeftWidth
                        + imgWidth