Crosshair cursor should not disappear while using "Select" tool

Using pixel.js in Safari, when I use the select tool (update: this also happens when using the brush, erase, rectangle tools), the crosshair cursor will disappear while I'm clicking and dragging. On mousedown, the cursor stays as crosshairs, but as soon as I move the cursor, the crosshairs are replaced with the i-beam cursor that I recognize from mousing over selectable text in other applications. Ideally, the crosshairs should remain while clicking and dragging.

(originally raised as [#864](https://github.com/DDMAL/Rodan/issues/864) in DDMAL/Rodan)