Activate Fill in mode

Hello everyone!

I just simply want to activate the fill in mode on segmentation editor. I want to be able to draw a circle and get it filled automatically. I looked everywhere for instructions which all brinigng up Tool Options → Mode but i cannot fine the Tool Options. I even search in Settings and there is no User settings there. Anyone please who can help how, where can I activate the fill in mode or any other simple way to get a closed loop filled in on the Segmentation Editor?

Thanks in advance for the help.

This feature is provided by the Draw effect (works only on a single slice in 2D, allows freehand and polygon drawing) and Scissors effect (works in 2D - single or multiple slices - and also in 3D).