in
http://demos.telerik.com/kendo-ui/datepicker/index
which is the

DATEPICKER
demo

change attribute in label tag from 

"<label datepicker="start">Show ..." 

to 

"<label for="datepicker">Show ..." 

Reason:

I don't know what the datepicker="start" attribute is for the
<label> tag and I think it is an error
and should be
for="datepicker"
which is a valid attribute for the <label> tag
and makes the cursor move to the datepicker input widgit if the label is clicked.