...When it starts, apart from the clock itself, a small tray icon appears. This tray icon can be used to call the clock configuration dialog. Also this dialog can be called using clock context menu.
Sources (v5) are hosted on GitHub: https://github.com/Kolcha/DigitalClock5
You can create your own skin! See this link for details: https://sourceforge.net/p/digitalclock4/wiki/How%20to%20create%20skin/
NOTE: do NOT download any .rar or .exe files marked as my software, these files are NOT made by me and I'm not responsible for their content