I find it quite difficult to dock windows on the side of the screen:

1. Open a browser window.
2. Drag it by its top to the right edge of the screen until you get the docking outline.
3. Take your finger off the touchpad. If you happen to move the pointer just a single pixel to the left while you're releasing, the window won't dock and you instead end up with it normal-sized and mostly offscreen.

We should allow the pointer to move a few pixels away from the edge of the screen before we cancel docking.