widget_calendar(3tk) on Linux
The text 25ed03f3120e, as Debian 9 (Stretch), Debian 8 (Jessie) shipped it.
Calendar Megawidget
Flags it lists
-
-command -
-dateformat -
-firstday -
-font -
-highlightcolor -
-language -
-shadecolor -
-showpast -
-textvariable