Controls
Desktop:
Tab Add child to selected
Enter Edit node text
C Collapse / expand
Del Delete node
Esc Cancel / deselect
Scroll Zoom
Drag node Move (adjust branch)
Drag canvas Pan
Dbl-click Edit text / New root
Mobile:
Tap to select / place
Drag node to move
Drag background to pan
Pinch to zoom
Drag nodes to control branch direction & length