Now you can calc times.
So if you want to calc 23s + 1m 23s you can simple type ti :23+1:23 in Krunner and get the Result.
If you work with ":" you can let the leading "ti" simply away.
Now you can also use the hours format to calculate: 2.3-2.0+0.1 and you can use a mixed format: 2.3+::12-00:01:00
and so on!
And at last but not least you can convert between the two formats!
To install the runner script just type in the terminal:
plasmapkg -i clockcalc.zip
After that you have to restart KDE or only krunner.