Hi,
can't test just now with Kubuntu 16.04 because my SSD gone broken. With Ubuntu Gnome 15.10 Opera not open from Enpass Help -> Online Help.
Getting this to terminal:
raimo@kone-2:~$ /opt/Enpass/bin/runenpass.sh
qt.network.ssl: QSslSocket: cannot resolve SSLv2_client_method
qt.network.ssl: QSslSocket: cannot resolve SSLv2_server_method
libpng warning: iCCP: known incorrect sRGB profile
libpng warning: iCCP: known incorrect sRGB profile
QLayout: Attempting to add QLayout "" to QPasswordEdit "", which already has a layout
QSoundEffect(pulseaudio): pa_stream_write, error = Invalid argument
libpng warning: iCCP: known incorrect sRGB profile
libpng warning: iCCP: known incorrect sRGB profile
libpng warning: iCCP: known incorrect sRGB profile
opera: /opt/Enpass/lib/libssl.so.1.0.0: version `OPENSSL_1.0.2' not found (required by /usr/lib/x86_64-linux-gnu/libcurl.so.4)
opera: /opt/Enpass/lib/libssl.so.1.0.0: version `OPENSSL_1.0.2' not found (required by /usr/lib/x86_64-linux-gnu/libcurl.so.4)
Every try to click Help -> Online Help gets new line, same as last 2 lines and Opera is not opening.
If Firefox is default browser in Ubuntu 15.10 Gnome, Enpass works fine, no any messages to terminal about browser opening.