click select · shift+click add · alt+click select parent
drag on empty space — rubber-band select
drag a handle resize — corners both axes, edges one · shift uniform
↑↓←→ nudge 1 unit · shift+arrow nudge 10
space+drag or middle-drag — pan · scroll — zoom
ctrl+Z undo · ctrl+shift+Z redo · esc deselect
Dragging follows the mouse 1:1 on screen. Arrows step whole units in the element's own coordinates, so the numbers stay clean at any zoom.
Nudge only ever adds or edits one attribute: transform on SVG elements, inline style transform on HTML ones. Everything else in the file comes back byte-for-byte.
Resizing writes a scale() into that same transform. On SVG that scales stroke widths with the shape — usually what you want for a leader line, but worth knowing.