Currently the widget will only accept a number for width and concatenates px to the value. It would be nice if it accepted units -- px and em would be great to start with. This would fix issues users with different font sizes in text-based widgets.

I think it's enough to have the em support for now. Given the future plans of the SDK which will put the widgets in the navigation bar, gives a totally different behavior. I don't have the link to the UX mockups handy but there was a blog post about it recently if you are curious.

Sorry, the comment 1 should have gone to the memchaser issue tracker not this bug.

We're waiting to get some guidance from the UX team before we prioritize this.

Stephen, can you give some feedback on this in light of the new widget guidelines we're planning?

Waiting on Matteo to look at this

This bug is pretty trivial to implement, we could assume is pixel if we pass a Number, and just use the unit we pass if it is a String. However, before implementing it I'd like to have some feedback on this from Stephen.

Working on some additional designs and thoughts for this.

I'm assuming this bug is a WONTFIX, because Stephen suggested fixed width (in pixel) for Widget, see https://bugzilla.mozilla.org/show_bug.cgi?id=645506#c20.

Matteo, a wontfix would be fine for the widget icons in the upcoming part of the navigation toolbar. But for addons which will have their own toolbar it would still apply. Especially if you are using any text in it to display the content. Given that we do not know the font size selected by the user the width will be different. So specifying it with px isn't a way which would work.

I honestly think this bug is a WONTFIX in any case. The use case you describe, will fall into bug 645506 if we decided to implement it for Toolbar's widget. If you have different use cases, let me know!

Fine with me if that's the case. But if bug 645506 is marked as wontfix this bug will still be remain valid.

Henrik, I added a comment to keep trace of that, in order to avoid to forget: https://bugzilla.mozilla.org/show_bug.cgi?id=787390#c1 let me know if it's fine to you, and feel free to add anything else you think can be useful!