First of all, great job by implementing some of the new features (DPR, screenshot, etc.)
Some things which are not “optimal”:
The new UI wastes a lot of space on the top.
The new UI size and font-size could be larger.
Actually its not possibel to write the slash character or the single quote character on the german keyboard layout when the RDM tool is open which is quite annoying. (It will open the search-field instead.)
“middle click” or “ctrl click” to open a link in a new tab is not possible anymore.
No custom device sizes anymore?
The device selection dropdown should maybe be put up top to the other options.
Hmm, this might be tricky since we plan to pack more information into the UI going forward. I’m not sure what the right balance would be here.
Yes, that’s a known issue. I believe all keyboard layouts are affected.
Thanks for pointing that out, I wasn’t aware of this! I filed a new bug for this issue.
It’s true that the initial release that shipped this new RDM UI (Firefox 52) does not allow custom sizes. However, we added a more powerful custom device mode to Firefox 54 that allows setting more than just the size, such as the user agent. Here’s a post about this. I would recommend installing Firefox Developer Edition, so you’ll have this change and other DevTools updates more quickly.