Drag the ringed tips of F(e1) and F(e2) to change the matrix, or click a matrix entry to type a value. Scroll to zoom, drag the background to pan, click to pin x or release it. While pointing or dragging, press Shift to temporarily switch snapping on or off, and Ctrl to temporarily switch unit vectors on or off (the Snap and Unit buttons between the planes switch them for good).Use two fingers to pan and zoom, tap to pin x or release it, and press and hold the picture to move it. The Snap and Unit buttons between the planes switch snapping and unit vectors on or off (while pointing or dragging, only for the moment).
The colour theme and the sizes of the planes are not saved.