Display mode.
In the standard (editing) mode you are forced to see the cursor and the upper message on the displayed view:
Now you can remove the cursor and the upper message from the canvas by pressing the 'D' key:
This is useful if you want to save the current view into image file. You can take a screen-shot or - if you run mki3d in the web-browser - you can save graphics on the right-mouse-button pop-up menu.
(I have implemented this feature, because I wanted to make some stereoscopic views that don't look like the cursor's selfie ;-)
Pressing any key resumes standard display mode for further editing.