FIX: Date & Time formatting in Options default preset cannot get it back if change it (fixes #1225)

src/frames/foptionsfilesviews.pas

@@ -150,6 +150,10 @@ begin
   cbHeaderSizeFormat.Items.Assign(cbFileSizeFormat.Items);
   cbFooterSizeFormat.Items.Assign(cbFileSizeFormat.Items);
   cbOperationSizeFormat.Items.Assign(cbFileSizeFormat.Items);
+  if cbDateTimeFormat.Items.IndexOf(DefaultDateTimeFormat) < 0 then
+  begin
+    cbDateTimeFormat.Items.Insert(0, DefaultDateTimeFormat);
+  end;
 end;
 
 procedure TfrmOptionsFilesViews.Load;

src/uglobs.pas

@@ -723,6 +723,7 @@ const
 var
   gConfig: TXmlConfig = nil;
   gStyles: TJsonConfig = nil;
+  DefaultDateTimeFormat: String;
 
 implementation
 
@@ -751,7 +752,6 @@ type
   TLoadConfigProc = function(var ErrorMessage: String): Boolean;
 
 var
-  DefaultDateTimeFormat: String;
   // Double Commander version
   // loaded from configuration file
   gPreviousVersion: String = '';