Handle WM_PRINTCLIENT.
Don't use SelectClipRgn in WM_PRINTCLIENT.

diff --git a/dlls/comctl32/header.c b/dlls/comctl32/header.c
index ae611b9..522aa81 100644
--- a/dlls/comctl32/header.c
+++ b/dlls/comctl32/header.c
@@ -1717,6 +1717,7 @@
         case WM_THEMECHANGED:
             return HEADER_ThemeChanged (hwnd);
 
+        case WM_PRINTCLIENT:
         case WM_PAINT:
             return HEADER_Paint (hwnd, wParam);