Great addon. Does what you'd expect. My only question is, when will it support Firefox mobile view? That would be the only thing I'd say it is missing.

excellent, maybe we would like a screen percentage measurement?

Consider allowing to increase the width & height after are created the square or rectangle, you can not create form first select the exact size with the mouse (the edges to become editable when you put the mouse over the edges to show an double arrow which to allow to increase or decrease the size and add check-mark who stop the edit and after to can move on the screen your created figure).
To can save as predefined figure to can load in other tab/window!
Scenario: A customer tells you that the distance between the title and the photo is not exactly the same as on his competitor's website and he wants the same distance. If you can save a figure created as a predefined (by giving it a name), you can load the same figure on the other tab/window and to show him if is exactly or not, and you do not have to recreate it again.
To can generate measurable figures in units, for example: create a figure of 24 pixels width and 4.5 pixels of height.

Es bonita y funciona muy bien. Tiene un uso residual pero para el frontal de las webs es necesaria muchas veces.

It´s a great tool, keep rock on!!!! Slutes from Barranquilla Colombia :D

what is the keyboard shortcut for it?How to activate it with keypress?

The extension is pretty handy and has helped me even with static UI images. It would be helpful to be able to resize the dimensions after the mouse drops though.

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Simple and useful extension, but it is not enough drawing functions area by clicking on the page element. Stretch accurately is difficult, and requires more time than a click.

I downloaded this new version, compatible with FF57, but the icon that appears in the toolbar is GI-NORMOUS. I loved the old version and suspect I'll love this one. But please fix it, or give me some idea of what I may be doing wrong (if that's the case). (I'm using FF56 with Mac OS 10.11.6.)

Why does a ruler need to "Access your data for all websites"?

I didn't install it so I just gave it a 2 to be fair but wanted to add this as a warning to other users.

UPDATE: Thanks for the reply and thanks for modifying the plugin to address the issue. I've changed my rating but I'll leave the initial review above so others can have context for your reply and also see how quickly your addressed the issue.

Sort of basic but it does what it's supposed to.