Stylus Paper от Nicolas B. Pierron

This addon, when enabled, overlays the largest scrollable area with a transparent drawable surface. This surface area can then be painted with variable width stroke using a stylus pressure.

The paintable surface is anchored on the content that it overlays. This implies that any drawing will scroll with the page that it overlays.

The paint/navigation mode can be toggled on/off, which let you access elements of the content for following links, or interacting with the web site.

Features:
* Stylus Pressure: When drawing, the added 'ink' will change width based on the pressure of a stylus.
* Scrollable: Objects which are drawn will follow the overlayed content.

Keyboard Shortcuts:
* Ctrl-Z : Undo the last paint action.
* Ctrl-Shift-Z : Redo the last undone actions.
* Ctrl-X : Toggle between navigation and Draw mode.

Permissions:
This addon requires some permissions from the user to behave as expected. The following is the list of permissions requested from the user, and why they are requested:

* activeTabs: This permission is used to enable this addon only on the current tab. When the addon is enabled, the current tab is intrumented to add a drawing surface. The instrumented active tabs does not communicate back to the extension, nor does it creates extra network trafic.