It works, but it's cumbersome to use. Alter marking the text, it's necessary to open the extension's configuration tab to select a colour (unless using the same colour for everything), then hitting the shortcut key. Removing a marking is not possible, one has to select the Page's background colour as highlight and mark the text (good luck figuring it out if the Page is not white or black or some other obvious hue...)

It's exactly what I was looking for... except it lacks control.
I want to highlight words, not paragraphs. This is difficult to do.
Perhaps some of my other add-ons are causing it to play up?

It has almost got it right; but I'm going to keep looking.

Could very easily be the best highlight addon BUT it causes the cursor to jump to beginning of line when typing in web text boxes such as Twitter/Facebook & makes typing nigh on impossible. Issue reported on Github but developer taken no action.

Needs the ability to remove the highlighted text.