key shortcut for clearing selection

[Karel]

Hello,

when I mark some files using the insert key, or using + and a typing a
regular expression, I know I can invert the selection using *, but how
can I clear all selections all together ?

Until now, I have done it by going up the parent directory and then
coming back again. But that does not seem to be the most efficient way.

is there a better way to clear all selections ?

Also, is there somewhere a complete cheetsheet with all the key shortcuts ?

thanks,
Karel