CLT & left traces

Why clt leaves traces after itself? I foud “opera.exe__” in Opera’s directory after CLT run.
What else can CLT leave after been run?
Can CLT developers answer this regarding registry and files and other objects possibly modified by CLT?

Also some 3/4 files “~xxx.tmp” in %temp% dir is not a big deal.


Here it renamed firefox.exe to firefox.exe_ , created own firefox.exe and left it instead of original. Spent some time to figure out what happened and fix things :-\