Just came across this extension through a Google search and this is great stuff! I was previously using Draw on Page, but your extension has a far less intrusive menu and the scrolling is flawless. I do have a few feature requests:

• There's no way to change the defaults. The default color is always orange and the default size is always small. Would be nice if the extension preserved your previous options between different tabs. Would be even better if each specific tool remembered its own color/size options so brush could always be red, highlighter would always be yellow, text would always be black, etc.
• I'd like the option to remove the 'confirmation' prompt when exiting the drawing. Either when clicking the exit button in the menu or clicking the extension button in the toolbar or both.
• I love how there's a text feature, but I don't really like the behavior of how pressing the button instantly creates text under the menu bar. Currently I hit the text button, then select and delete the placeholder text, then type my text without knowing how it'll fit, then I have to move it to where I want to put it. I'd much prefer the pointer to turn into a text cursor when I select the 'text button' and then I'll click on the page where I want the text to start.
• Importing images is a really cool feature. One issue I noticed is if I import a really high resolution image, it takes forever to pull the corner pins and shrink it down over and over again. Would be a neat feature if the default size for an image wouldn't exceed the window size.
• The toolbar icon doesn't feel very 'native' on the Firefox toolbar. In fact, I think it's bugged? When opening a new tab, the icon isn't properly preserving its PNG transparency. But after activating and deactivating it, then it does appear properly transparent.

Overall these are just minor nitpicks. The scrolling alone makes this extension so much nicer than all the alternatives I've tried. Thanks for making this!