Under Yosemite, shifting two fingers over the trackpad of the MacBookAir made for
gentle vertical or horizontal pans of the LibreCAD drawings
Now under El Capitan 10.11.5 the two finger touch induces a violent zoom-out
which makes LibreCAD unworkable (I tried 2.1.0 'old' versions, same misbehavior).
Which is weird is that it still moves up and down the file lists and the Firefox browser pages
(but no longer laterally)
Is it possible that El Capitan is sending sligtly modified trackpad commands that LibreCAD
(or QT) can't correctly interpret ?
If all your custom toolbars / menus are missing,
and the options have changed back to default:
I'm guessing OS X changed how it stores settings,
and it's created a new file now that you upgraded.
Or maybe it got rid of all your old settings files.
In Finder: Shift+Command+G
Note the modified date for com.librecad.LibreCAD.plist