Fantastic add on! Just about perfect for highlighting within current Firefox. I have one issue that would make this 5-star add-on a 6-star: allow Custom Markers to appear under Customize Shortcuts. I want all my shortcuts to start with Alt but Customize Shortcuts does not show my Custom Markers. My desired end state is Markers for alt-1 alt-2 alt-3 alt-4 with alt-d as delete. With Textmarker 3.10.0, the alt- modifier can not be used with Custom Markers like alt-1 and alt-4. Note, the whole issue with having to use Alt- is because I use "Search for text when you start typing" which means just using 1, 2, 3, 4 for markers also causes the Firefox search to pop up for that number. One other feature would be nice: Textmarker right click pop-up option to delete all markers on current page. Anyway, awesome highlighter, easily the best option for Firefox webextensions, maybe the best Firefox hightlighter ever!