Add custom date format

When adding "Node created date" or "Node last updated date" from Add content -> Node in Panels there are only the standard date formats (short, medium and long) to choose from.

In Views there is this very flexible "Costum" format as well where you can use the PHP date formats any way you want. My feature request is to add this custom date format to Panels.

There is a workaround (although less flexible); add a custom content and use substitutions like %node:day %node:d %node:month %node:yyyy (or %node:mod-day %node:mod-d %node:mod-month %node:mod-yyyy for modification date).