patch 8.2.2160: various typos

Problem:    Various typos.
Solution:   Fix spelling mistakes. (closes #7494)
diff --git a/src/gui_xmdlg.c b/src/gui_xmdlg.c
index 04996ef..ad3146a 100644
--- a/src/gui_xmdlg.c
+++ b/src/gui_xmdlg.c
@@ -497,7 +497,7 @@
     }
 
     /*
-     * Now loop trough the remaining lists and set them up.
+     * Now loop through the remaining lists and set them up.
      */
     for (idx = (int)NAME; idx < (int)NONE; ++idx)
     {