[kde-edu]: KMPlot patch

[Matthias Messmer]

Hello!

Rivo Laks wrote:
> The attached patch hides function's derivatives and integral when the function 
> itself is hidden.

I can think of situations when i wanted to show the derivative but not 
the function itself, for instance; a worksheet to study graphical 
integration/derivation of functions by measuring areas under the plot or 
using tangents.

Best regards

Matthias