Hi, it maybe due to where you are getting your compile from. Is there another place ? Can you user Mozilla's ?

• https://www.mozilla.org/firefox/all/

thelta said

After i clicked three dot, download or options button, they don't respond to click. I can open them in menu bar or using shortcuts. I already tried both safe mode and refresh and there is no change about problem. I'm using Firefox 61.0 OS: Ubuntu 16.04.4 LTS x86_64 DE: KDE5 WM: KWin

You mean Preferences as Options is the equivalent on Windows.

I know the Ubuntu provided build of Fx 62.0b6 had issues with installing Extensions and was fixed in 62.0b7 and on. I know Debian had issues using Dictionaries for the spell checker in the first build of Fx 61.0 but was fixed in second build of Fx 61.0

So it is possible the particular Fx 61.0 build you have from Ubuntu has issues.

I tried Firefox build from Mozilla's site. Still doesn't work. But what I found is problem isn't buttons doesn't work, they actually work, however they don't show the UI. For example after I press three bar button, if I press settings button then settings opens.