Brush tool does not work on Windows Firefox with tablets or touch screens

[adroitwhiz]

Expected Behavior

When using the brush tool with a drawing tablet or touch screen, it should draw a brush stroke as you drag your pen/finger across the tablet/screen.

Actual Behavior

In Firefox on Windows, with touchscreen support a.k.a. Windows Ink enabled (you can tell if it's enabled by looking for the halo that appears around the cursor when you start dragging the pen/your finger), the brush tool only starts drawing once you stop dragging the pen/finger, and requires another drag to stop the drawing.

Steps to Reproduce

On a Windows device with a touch screen (e.g. a Microsoft Surface) or with a drawing tablet plugged in and in "tablet/touch mode" aka Windows Ink:

1. Open the paint editor
2. Switch to the brush tool
3. Attempt to draw a brush stroke

Operating System and Browser

Windows + Firefox