Can one of the admins verify this patch?

• the overflow scrollbar on the RHS of the input field seems to be stuck on?
• ...likewise on the autocomplete selection
• the padding of the autocomplete doesn't match the design (compare the height of 3 rows between @antikewl's zeplin design and the implementation)
• the autocomplete doesn't take up the full width (but this may be deliberate?
• the entirety of the invite tile should probably be a hit target
• it would be really nice if tab completed manual mxids (as well as space and comma), given tab-complete is our common idiom here.

Otherwise this is looking really good! Unsure whether to merge now and apply the cosmetic tweaks after the event or wait for this before cutting the freeze...

Final question: is a deliberate design that the 'User ID, Name or email' prompt is always on the last line, rather than flowing inline and moving over the autocomplete bar to match? (superficially, removing the width of the textarea, setting display: inline-block and putting a relative offset on the autocomplete bar seems to work)

(merged, although the stuff above still needs to be addressed somewhere)

moving the feedback to #1882 so it's not lost.