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As it is now, it's mostly unusable on a screen that's 1280 wide since most of the functionality is hidden offscreen. That's mostly Mozilla's fault, but hopefully the developer will find a way around their incompetence.

previously im firefox 17 user, it works, now im upgrade to 52.9.0 and the toolbar is gone, what should i do ??

This provides a lot of very useful tools, but if it's pinned to the overflow menu, the panel it opens in is too small to use them all. There doesn't seem to be a way to resize the panel or scroll within it.