Treeview plus/minus

[George Ginden]

Talking about the plus / minus symbols in the treeview control...
Why with a size of 16 the plus symbol looks more like a small circle 
than a cross ?
If I change the size to 18 the plus is drawn correctly
Does anybody knows anything about this ?

Regards.

@@ -2329,7 +2330,7 @@
            SelectObject(hdc, hOldPen);
            DeleteObject(hNewPen);

-           if (height < 16 || width < 16)
+           if (height < 18 || width < 18)
            {