Based on "datefield.tcl" by KPV from Feb 07, 2002 - initial revision
I give my propose for revision 0.3 (with no warranty etc.)
- support more keys and the mouse wheel
- add option -format to support 3 date-styles:
	"%d.%m.%Y" (for German)
	(for English, standard/default)
	"%Y-%m-%d" (for ISO)
- each widget may have another format (stored on creation)
See the already coded file attached
It was successful tested under RedHat and Windows 7 & 10
with ActiveTCL and